Ohhhhh.... Haven't seen or gotten a BSoD in 7 yet.
Let me ask, when do you get it? When it tries to start or when you are doing stuff?
Well the first time it happend was yesterday I believe I figured i should update my video cards driver to the latest available so i did and
my machine kept giving me bsod so i did a fresh install of windows 7 with drivers i know work, (im new to windows 7 i just switched to it last Tuesday Xp disk was scratched). And all was running fine until just about half an hour ago i was watching some star trek enterprise on media centers online tv and installing fallout 3 and it crashed with the same error i was getting yesterday. "irql_not_less_or_equal"
Check the memory. Check the settings in the BIOS and make sure that the timing and the voltage is set to their spec (normally on the side of the memory sticks). Once that is done, make sure they are seated in their slots properly.
If that doesn't fix it, google and run Memtest 86+ (they have a bootable image). Run it for a good 3 or so runs and if it passes its good and might be the HDD. If it doesn't pass then take out one stick at a time and test each one to find the bad stick.
If it does pass then run a HDD tester. I prefer Spinrite.