Your error (IRQL not less....blah, blah), continues to indicate a driver load error, yet they are the same driver. My guess would have been that this means a hardware failure, but since the error continues on both videocards, I think we have to rule out video hardware, leaving us with memory, motherboard, or maybe corrupt vga.sys file.
I'd like to try two things at this point.
First, navigate to c:\windows\system32 and find vga.sys. Right click it, choose properties, and report back the version number, date, size...anything you can
Second, download memtest86+ from here:http://www.memtest.org/
Get the Pre-Compiled Bootable ISO (.zip)
If you do not know how to burn a disk IMAGE (not burn a file), download the iso recorder powertoy from here:http://isorecorder.a...nman.com/v2.htm
Install it, reboot.
Now, extract the memtest86+ ISO file from the zip, then right click it, and choose COPY IMAGE TO CD.
This will burn the image to the CD, and it is bootable. Leave the CD in the drive, reboot. If the memtest does not start on reboot, check your system bios to ensure that CD-ROM is first in the boot priority list.
Report back any memory errors (let it run through atleast three passes--take an hour or so)