New System Blue Screen Blues

Ok so I built a new system and I got it up and running, installed windows (vista) went ok and then installed the chipset drivers from the disk that came with the computer. Then installed the graphics drivers and downloaded AVG. I then went to windows updates and started doing my updates to get windows up to date and as soon as I did I got the blue screen of death.

this is my system:
Intel core i5 750
p55m-ud2 gigabyte
coursair 2x2 gb ddr3 xms3 1600
XfX radeon 4890 gpu
and a WD 1tb green sata 32 mb

any time I try to access windows update, or really anything, or even let the system sit for 5 minutes, I get a blue screen of death, which may or may not include a technicolor scramble. Then I get one of several possible stop error messages which may or may not include
irql_not_less_or_equal
or a any one of several others.