I formatted my pc purposely to install windows 7.after this,windows fail to install so i re-install windows xp.after this my wireless fail to work.when i tried it says'no supported wireless adapters available in the system.my pc model is acer 1642z.pls help me

You can perform the format when installing Windows 7. Boot from the Windows 7 installation media, then remove old partitions and perform full format.

Hello, this is how I dual boot my laptop with windows xp and windows 7

1. Backup all you important files, use an external hard-disk if possible
2. Make sure you have two drives or partitions: usually drive C and D
3. Insert your xp cd, do a quick format of drive C and install
4. Boot into windows xp and format format drive D if necessary
5. Insert your windows 7 DVD and follow the prompts. When it asks you to upgrade or new install, choose new installation
6. When you are asked to choose a location choose drive D
7. Complete your windows 7 installation
8. Thats it, you can now install drivers and programs

When installation is complete you will see both os options: windows 7 and previous version of windows (i.e xp)

I have done this numerous times without the need for any other step or software. The only rule is to is to install xp first, then windows 7.

All the best

What OS you want to install
For Windows XP visit this link http://howtoformatacomputer.com/format-windows-xp
For Windows Vista http://howtoformatacomputer.com/format-windows-vista
For Windows 7 http://howtoformatacomputer.com/format-windows-7

Hi,
Yes you can install windows xp in windows 7.
Windows XP Mode is a virtual PC image of Windows XP Service Pack 3 that could be run on Windows 7 Professional, Enterprise or Ultimate versions. Applications installed into Windows XP Mode could be run in Desktop Mode or Seamless Mode. In Seamless Mode, applications appear to run natively within Windows 7, but they are actually running inside the Windows XP virtual machine. Windows XP Mode might also provide additional integration that traditional Virtual PC images might not be giving. Applications installed on the Windows XP image could be exposed to the Windows 7 Start menu. Applications run in seamless mode is having automatic access to the Windows 7 known folders like Documents, Pictures, Desktop, Music, etc. Also the Cut-and-paste is enabled between native Windows 7 applications and those running in Windows XP Mode. Applications running in Windows XP Mode might also access your Windows 7 network connection and USB devices.

You need to enable boot from CD in the BIOS.

#1 Use windows backup in Windows 7 to create a full system backup of the OS to DVD or a removable drive. (And well as any data on any other partition)
#2 Repartition drive to roughtly 50 50 split
#3 Install XP to partition 1, Install 7 to partition 2 then restore the backup of 7 to partition 2,

I think your problem is this, you try to install Windows XP with a pre-installed Windows 7---windows doesn't accept downgrading of O.S., so the best solution on this would be to erase Windows 7 or format the hard drive and install a fresh Windows XP.

You will have to boot of the XP install disk and reformat a FULL NTFS format, first, that will enable you to wipe the drive and install XP. To save an email, or any file to a flash drive, simply copy/paste or drag and drop onto the drive, the drive must be Formatted first, format FAT32. OR when asked for location to save, point it to the flash drive as normally done.

You need to partition and format the hard drive and then do a fresh install of Windows XP or Windows 7

sys file from the cd is corrupted...try wd any other disc