Random BSODs while and afer OS install, multiple OS's (mainly Win7)

I think this is gonna be a hell to diagnose..

First, my hardware:
  • Processor AMD Athlon II X4 640 AM3 BOX
  • MOBO: Socket AM3 Gigabyte GA-880GA-UD3H
  • DIMM PC-1333 DDR3 4GB Kingston KVR1333D3N9/4G CL 9
  • GFX: GeForce GTS 450 1GB HDMI&DVI Gigabyte
  • PSU: Delta AB-A 500W (same as chieftec)
  • HDD: Seagate Barracuda 500GB

Now my problem:
Everytime I try to install win7 (evaluation version, 64 bits) I get a blue screen of death.
Now it would be nice to privide you iwth some error codes, but the tricky part is almost everytime it's something else..

Some of errors I got:
Stop 0x0000000A or IRQL_NOT_LESS_OR_EQUAL
Stop 0x00000023 (that's when I was installing win7 from USB drive)
Stop 0x00000050

But there were more of them for sure.
Some strange things happend when I tried to install XP too.
Only live CD linux (knoppix) made it running.

Now the things I've done and tried to do:
-I've run a Memtest86+ v. 4.10 - Successfuly passed.

-I've tried to install win7 both from DVD and USB stick.
(Dunno if that matters but it crashed mainly around 50% of installation)

-I've run chkdsk (it found some corrupted files after failed win7 installation, but none bad sectors - but I still think it would be nice to check disk with some other software)

-formatted HD twice (NTFS)

-tried to check / uncheck some things in the BIOS.

The win7 got installed successfully only the first time (also after some BSODs), but after getting into system and trying to check some log files I got... a BSOD.

For me it's almost obviously a hard disk problem, but wouldn't chkdsk find any bad sectors / errors while scanning?

Help would be greatly appreciated.