i install win7 on my dell gx280 , but my pc is running slow , so i try to reinstall win xp again but the blue screen appears with error , so i install win 7 again , how can i solve this error and install win xp again .mustafa

Excellent point you made! May I sugest setting your BIOS to IDE mode. In the BIOS you will have a choice of IDE , AHCE and RAID. You may have to search for it since not all BIOS are the same.

"You may not be able to install XP or Windows Server 2003 to partitions created with Vista Disk Management." You cannot install Windows XP successfully after you use Windows Vista or Windows PE 2.0 to create partitions on a hard disk You might try deleting the partitions, then recreating XP compatible ones before reinstalling XP. But before giving up, if you provide more details, somebody here might be able to help you improve your Windows 7 performance. For example, your dell gx280 contains an Intel Grantsdale chipset. Did you update your drivers yet? Who's Zed? Zed's dead, baby. Zed's dead. - pulp fiction

my drivers is up2date, but i update my bios from A03 to A08, mybe this update makes error??mustafa

BIOS update is probably not the causing your blue screen. Most likely it's how you have it configured. If you can find the setting for sata mode and set it to "IDE" 9 times out of 10 will work.