Hey Chickensoup,
Sounds like you wish to use the system restore function in Windows. Check out
here for an easy to follow, step-by-step guide.
I know it's not the best guide in the world, but I was unable to find any better!
Quick guide is:
- Press F8 upon boot to enter safemode.
- When in windows click Start.
- Type system restore in the Search box, and then press ENTER.
- Keep pressing next and then choose the date closest to 2 weeks ago.
- System will reboot and problem should be solved.
Better yet. Go wake your brother up and force him to do it!
Hope that helps!
Also, I should add that it is legal to download torrents such as Windows XP or Windows 7 if you are actually going to use a legitimate CD key.