Have you checked for bent pins on the monitor cable?
I believe he checked the monitor on his moms computer if I read it correctly.
From what I understand you have ruled out the video card and monitor. But when he gets to Windows XP it drops out?
Wait a minute... It could be a faulty PCI-E it sounds like... If the video card worked fine on your bros PC then its something with yours and I think we can rule out Video card all together.
Try this, Go into the BIOS and switch back to on-board video, its not as powerful and it won't be able to do all the things you want it too but it is possibly a temporary fix and can help us rule out what is causing it.
Edited by xXAlphaXx, 11 June 2008 - 03:09 PM.