My laptop and the vista to xp disaster

hey, so I bought a laptop (P105-S9339 from Toshiba) and it came with vista...
And hey its just another OS, il just completly format the harddrive and load windows xp, ive got all my drivers from their website... Im golden...\endsarcasm

Well luckily for me vista is a monster and it wants my computer, I am trying to get XP to work on a laptop that had vista intalled on it prior, and the drivers is what is killing me. I cant get the video card (GO 7900 GS) to install, ive gotten the .inf and tried that isnt working.

Has anyone tried to downgrade from vista and succeeded or is that just fantasy? I got this thing while im home on R&R leave from Iraq and I have until may 2 to fix this thing or its not gettin fixed until febuary 2008 lol

Please help me out someone... Thanks :cry