STEAM Crashes? Display driver fails?

Ugh well i finally got my first build done and working after a full month of 2 RMAs for my motherboard. Its rather odd, but i couldn't find any solutions so i thought i might post here.
So i installed a fresh copy of windows XP as soon as I got my PC running. All is well, i pop in my orange box disc to install, steam installs fine and the installation gets to the point of telling me to insert disc 2. i open the drive and *BAM* my screen goes black and keyboard and mouse becomes non-responsive.I thought my display driver failed, but I'm not sure. I have no choice to restart the computer. When i restart, every game for the orange box reads "download paused" which isn't a big deal. I figured this was one of those one time lock-ups, but i guess not after i tried again and again. I even reinstalled windows XP to see if that was the problem. It wasn't.
Also, i can't play any STEAM games either, like Half Life 2, other non-steam games work fine.
I'm a bit confused, and I'm looking for a solution.

~SPECS~
Intel Core 2 Quad Q6600 @ 2.4 Ghz
4 GB RAM (XP says 2.75)
ATI 2600 XT 256mb
nVidia nForce 780i SLI Motherboard
Thermaltake 850w PSU
400 GB Hard Drive