Multiple BSOD with seemingly no connection

I'm getting random BSODs at random points in time. I have litterally been asleep with my system on idle and it will bluescreen, or I can be chatting with my friends on IMVU, bluescreen. It just seemingly does this out of nowhere. There doesn't seem to be any connection in the things that trigger it and I've had several messages from the BSOD screen:
UNEXPECTED_KERNEL_MODE_TRAP
PAGE_FAULT_IN_NONPAGED_AREA
IRQL_NOT_LESS_OR_EQUAL
SYSTEM_THREAD_EXCEPTION_NOT_HANDLED
KMODE_EXCEPTION_NOT_HANDLED


Steps taken:
1. Memory Test (0 Errors)
2. sfc /scannow
3. Disc Check (rebooted and ran full check with fixes)
4. Virus scan (Avast! 7)
5. Rootkit (Found and removed, named something like twreg)
6. System restore
7. Driver Verfier

About the only things I haven't tried is replacing hardware and re-installing my system. I don't have any extra hardware to test and I can't really afford any extra pieces to test with. This started happening over seemingly nothing. As far as I can remember, I was doing the exact same thing I do every day when I suddenly got the first error. Any help would be very appreciated.

I ran furmark, instant crash. My computer had been on for a few hours so I ran it again. No errors after 30 or so minutes at 1280x1034. Temp got up to 78. I always have my CPU temp displayed, it averages 50 when on high load (t.j.max 70) I don't overclock, I've heard too many fried CPU stories. I clean the dust out of my computer frequently, I replace the thermal paste every other month. I only have one ram stick, so I can't try removing one. Memtest did pop up a "unexpected Interrupt - Halting" with a bunch of hex code.

Hard drive passed both diagnostic tests from the manufacturer.
Also, the computer parts are all two years old except for the GPU which is only about two months old.

If it helps any, right before my computer gives me a BSOD it ramps up as if I had just opened the most intense game in the world on ultra settings.

I switched my graphics card with the old one I had in my system. I never had a single problem with my computer up until a couple months ago when I put in a new Nvidia 460 GTX. When I did that, I got bluescreens a lot. Fixed that, and now they seem to be back.

Well see, that's the weird part. I had it replaced, they took it back and ran all the diagnostics on the first one and there was absolutely nothing wrong with the card. But every time I put it in my system, it tries to eat it.