Can I do a Full System Restore on a computer that previously had Windows XP & now has Windows 7?

Once you format/upgrade and install another OS, the old files and OS was gone forever. You cant get back the old OS by System Restore. System Restore is not for you. I am not familiar with Win 7, but I think it saves the older OS, check Microsoft website if it is possible to revert to older OS. You have to Reinstall the XP with a new Installer CD.

Its ussaly recomnded to reformate your drive using a program like Darik's Boot And Nuke also this can be dangerous if done incorectley, i turned of my pc before Darik's Boot And Nuke finishd and it completley broke my harddrive. But doing this would erase any rollback options and you would need a os disk, If ya can use the windows 7 disk instead that be good but

NO you really cant do that because your windows 7 will only contain the restore points since u installed windows 7. its same for windows xp also. it(windows xp) would contain only the restore points which were created during its time period.

YES you can because changing the operating system does not affect the original 'Recovery Partition' on your Hard Drive. That contains everything you need to restore it to factory condition. NOTE!! This will erase everything so you will need to back up any documents,photos.music, files that you want to keep so that you can reload them when the restore has finished!! Windows XP: Dell PC Restore Turn on the computer. During the boot process, a blue bar with www.dell.com appears at the top of the screen. Immediately upon seeing the blue bar, press <Ctrl><F11>. If you do not press <Ctrl><F11> in time, let the computer finish starting, and then restart the computer again. NOTICE: If you do not want to proceed with PC Restore, click Reboot in the following step. On the next screen that appears, click Restore. On the next screen, click Confirm. The restore process takes approximately 6–10 minutes to complete. When prompted, click Finish to reboot the computer. NOTE: Do not manually shut down the computer. Click Finish and let the computer completely reboot. When prompted, click Yes. The computer restarts. Because the computer is restored to its original operating state, the screens that appear, such as the End User License Agreement, are the same ones that appeared the first time the computer was turned on. Click Next. The System Restore screen appears and the computer restarts. After the computer restarts, click OK.