Windiws cannot access the disk

Which version of xp are you trying to install 32 or 64 bit ?

Your ability to install a second operating system on your Windows 7 system hinges on one thing: partitions. If your computer has only one partition, you can't dual-boot your system without erasing all information on your computer. Two hard drives, or two partitions, enables you to dual boot. Check this information first, before proceeding.

Click "Start" and type "disk management" into the search bar. Click on "Create and format hard disk partitions" in the list of programs to open "Disk Management." Look at the list of partitions and available drives. The information here will be different on every computer. "C" is your primary hard drive and active operating system partition, and this drive contains your Windows 7 installation. You can't install Windows XP here without formatting the system. Check for secondary drives and partitions in Disk Management. Your system may have a "D" or "E" drive. Some computer manufacturers create a hidden partition with recovery software: don't remove this partition. If you have a secondary partition called "D" with more than 2GB of free space, you can install Windows XP here. b> Installing XP b> Insert the Windows XP Setup disc into your CD or DVD drive and close any windows that appear. Shut down your computer with the disc in the drive. Turn the computer on and look for a message saying "press any key to book from CD." Press any key on your keyboard when this message appears. Most computers are configured to look to the CD or DVD drive first, before booting to the operating system. If your system doesn't recognize the disc, you will have to enter your BIOS and change the boot order. Look to your manual for information on changing the boot order. Press "Enter" on the "Welcome to Setup" screen to load the Windows XP setup program. Read the license agreement and press "F8" to accept. Windows will detect that an operating system is already installed on your primary partition and present a list of other partitions to install XP. Use the arrow keys to select your secondary partition ("D") and press "Enter" to confirm that you want to install XP here. Then choose what to do with the partition: leave the file system intact or format the partition using FAT32 or NTFS. Windows XP supports both file systems, but requires NTFS on partitions larger than 32GB. You don't need to format the drive to install XP. Follow the prompts on screen to enter your personal information, serial number, and date and time. The setup program copies files to your PC and reboots -- don't press a key to boot to the CD. When you have to operating systems installed, a DOS screen appears asking you to choose an OS; press the down arrow key to highlight Windows XP and press enter to complete the setup. You will have to choose this every time to boot into XP, otherwise your computer will boot to Windows 7 by default. Hope this helps.

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Read these tutorials, Link

If you want both OS you need to do a partition on the HD to proceed.IThat what i can figure from your quest.But if you just want XP just do a clean installation of it.

Perform a clean install of Windows XPA clean installation consists of removing all data from your hard disk by repartitioning and reformatting your hard disk and reinstalling the operating system and programs to an empty (clean) hard disk. For more information about important things to consider before you partition and format you hard disk and how to partition and format your hard disk by using the Windows XP Setup program, click the following article number to view the article in the Microsoft Knowledge Base:313348  (http://support.microsoft.com/kb/313348/ ) How to partition and format a hard disk by using Windows XP Setup programTo perform a clean installation of Windows XP, follow these steps:

1. Back up all important information before you perform a clean installation of Windows XP. Save the backup to an external location, such as a CD or external hard disk.
2. Start your computer from the Windows XP CD. To do this, insert the Windows XP CD into your CD drive or DVD drive, and then restart your computer.
   
   Note To boot from your Windows XP CD, the BIOS settings on your computer must be configured to do this.
3. When you see the "Press any key to boot from CD" message, press any key to start the computer from the Windows XP CD.
4. At the Welcome to Setup screen, press ENTER to start Windows XP Setup.
5. Read the Microsoft Software License Terms, and then press F8.
6. Follow the instructions on the screen to select and format a partition where you want to install Windows XP.
7. Follow the instructions on the screen to complete the Windows XP Setup.

If you have successfully installed Windows XP, you are finished. If these steps did not help you install Windows XP, go to the "Next Steps" section.

u can format in progress install new windows

If you have a valid Win XP Pro CD and want to install the operating system you'll need to format your hard disk drive. If you have allot of data on you're hard disk drive, (In Win 2000) Suggest you create a second partition within the free space of you're hdd and install windows XP Pro. Boot you're system with the XP CD. Pay close attention to the display screens. Follow the instructions for creating a second partition.
Format the new partition. (Quick). Install windows XP on the new partition. Once completed you can copy your personal data to win XP.
If you choose to keep the win 2000 partition and you do not wish to have a dual boot system than remove/delete the root files from the 2000 partition. These files; Autoexec.bat and Boot.ini. You're new XP Boot.ini should read like this;
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect /usepmtimer
Once you're satisfied an no longer need win 2000 use windows diskmgmt.msc from the run command to delete the win 2000 partition.
Win 2000 uses a FAT16 where Win XP uses the FAT NTFS.

Cheers!
Mike

compaq cq40 is one particular model from compaq which is literally designed for vista and when you want to install win xp ;it doesn't work becoz the BIOS block it;the only way out is to downgrade the system BIOS which is a risky thing.check your bios model and version and google for a lower version and download it and flash the ealier BIOS.gooogle more on How to downgrade BIOS

Hi there,
Enter BIOS Set CD rom drive to first bootInsert your CD reboot
folow the on screen instructions be patient, it may take up to an hour,  and then two houers to install drivers,
-> if you want me to find the drivers for you, plz state your computer name and model.


regards /Teis

You will need to fix the master boot record with the Windows XP Recovery Console. To do this, you will need a Windows XP install CD.

Here are the steps to use the recovery console:

To run the Recovery Console from the Windows XP startup disks or the Windows XP CD-ROM, follow these steps:

1. Insert the Windows XP startup disk into the floppy disk drive, or insert the Windows XP CD-ROM into the CD-ROM drive, and then restart the computer.
   
   Click to select any options that are required to start the computer from the CD-ROM drive if you are prompted.
2. When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
3. If you have a dual-boot or multiple-boot computer, select the installation that you must access from the Recovery Console.
4. When you are prompted, type the Administrator password. If the administrator password is blank, just press ENTER.
5. At the command prompt, type the appropriate commands to diagnose and repair your Windows XP installation.
   
   

In this instance, the correct commands are:

c:\fixmbr
c:\fixboot
The type exit after finishing then remove the Original OS CD.
The machine will reboot properly.

This will fix your boot sector

And All should be well

I know this problem, The HDD is a SATA disk, win XP setup cannot identify a SATA controller on it's own you need to load the driver (from a disk) so you may need to download it first. I think this is the correct link http://h10025.www1.hp.com/ewfrf/wc/softwareDownloadIndex?softwareitem=ob-51521-1&lc=en&cc=us&dlc=en&product=3369431&os=228&lang=en extract the files and burn to a CD or Floppy then run win XP setup by booting from CD you should see in the begining of win XP setup from CD it prompt you to press (I think) F2 to add RAID or SCSI Controllers, (this prompt is at the bottom of the screen) Then follow the propmts to load from the disk you made earlier. you should be able to select the controller from a list. (short list) you should then be able to continue and hopefully Win XP setup should now be able to see your HDD and give you choices about which partition (as per normal) you want to remove all partitions before installing winXP (you can then make whatever partitions you wish) Hope this helps