Vista 64 New Ram BSOD

Hey guys, 1st post, I have been running around for the past 12 hours
trying to find out why my computer is the way it is. I had Vista 32 Bit
with 2 Gigs of RAM. Wanted to get 4 gigs and was told to upgrade to 64
Edition, I did. My Specs now are, Intel Quad 3.4Ghz, 8800GTX SLI, 4 Gigs
DDR2, Dual Hard Drives. My problem now is a ton of hardware now wont
install, my external HD Western Digital, Integrated Flash Card Reader,
etc. They wont run. Also I am afraid to turn off my computer now,
because every time it boots it BSOD's so I have to go to "Last Known
Good Configuration" I am completly out of ideas. I did "Mem-Test" no
problems on the RAM I got the latest version of my BIOS, and my MOBO is
an nForce 680I SLI. Please help me out guys, I really appreciate it.

PS. You guys can check out my other post here
'Ahh! Upgraded to Vista 64bit'

Angelo Cosma