Originally Posted by lhuser
Actually, to 100% confirm it, you will need to download Memtest at www.memtest86.com
Burn to a CD or write to floppy and let it run. If you notice any errors, your RAM is bad. However, do one stick at the time...meaning to remove one. If one contains errors, but not the second, you can use your second stick for now.
I'll second this test, as it's the first proceduer I ever use while determining IRQL errors.
EDIT: Other big possibility is drivers, if you did something like replace hardware (motherboard, graphics card, possibly soundcard) without reinstalling windows, you can also get errors like this.