just follow this guide it'll help you
fisrst of all get the driver from here :
then follow this guide
Note: Installation of this driver requires the use of a floppy disk drive. If your computer does not have an internal floppy disk drive, an external USB drive can be used instead.
Download the driver file to the desktop, and then perform the following steps.
1. If you have not already done so, locate and double-click the D00455-001-001.exe file that you downloaded from the Internet and execute the file. Files extract to the C:\Cabs\D00455-001-001 folder on your hard drive.
2. Insert a blank floppy disk in the floppy disk drive.
3. In the C:\Cabs\D00455-001-001 folder, double-click F6flpy32.exe.
4. Click OK to start the disk creation.
5. The disk creation dialog box closes when the disk is complete.
6. During the installation of Windows you will need install this SATA controller driver. Press the F6 key on your keyboard to install a third party controller driver.
7. The Windows installation program requires the use of a USB floppy disk drive and the floppy disk that was created above.
8. The Windows installation procedure attempts to load the drivers twice; once directly after the F6 selection, and a second time after the installation files copy to the hard drive.
9. Select the "- Intel(R)82801GBM SATA AHCI Controller Mobile ICH7M" option as listed.
Note: To find the required selection it may be necessary to scroll down even though there is no indication to scroll down.
Note: If you experience any recognition errors during the installation, please reference this Microsoft Knowledge Base article KB916196. This article explains which USB floppy drives are supported by the Windows installation process. http://support.microsoft.com/kb/916196/en-us
Because the computer must have these SATA drivers when using a non-Gateway supplied operating system, these drivers are necessary and should not be removed.
just let me know