Hi, I got the very same problem (steam install):
The SSE splash-screen with progressbar on the bottom came and soon after the progressbar left, system said "application crash". This was in Win 7 Ultimate 32 bit, quad-core Q9550, GeForce 8800GTX, reboots and running as admin didn't work.
However I got it working after installing the latest drivers for the gfx-card from Nvidia (version 258.96), but now I'm blocked with the cd-key which isn't provided...