Corrupt Windows/Downloads + Can't Install programs

[Magic Chief]

Hmm well I have a problem. My system is really unstable. I just got a new board and memory back from RMA and still have the same problem. My memory tested out fine on Memtest. My hard drives tested out on Seagate tools and chkdsk, I even bought a new drive to see if that was the problem. Power supply is fine. Video card is fine. Samsung DVD-RW SH-S203B is new. I can't install xp x64 but I can install x32. The main problem is my downloads are corrupt, I can't download windows updates, I can't install java, flash, office 2007, adobe acrobat or any other program and most of all it has trouble installing chipset drivers, realtek sound/nic drivers, video drivers, etc. System is really unstable.
Mem 2.2v 5-5-5-15 2T Stock; New
CPU: 1.25v Stock
Video Card: Stock
DVD-RW: New but still had problem with multiple ATA/SATA drives
Hard Drives: Seagate 400GB and new WD 160GB SATA; IDE mode in bios
MB: Beta 12 bo2 bios, I uped my ICH vcores 1.12 and 1.60. Set to stock for now.

I have zero filled the drives, used one stick of memory in slot 4, updated bios ohh and installed windows 50+ times. Xp x64 fails to copy files during installation and vista x32 gets bsod error. Xp x32 installs but i can't do anything. Used UBCD utilities and still not luck. It can't be the board or ram because they are both new. All help will be greatly appreciated.

Intel Q6600 (G0)
Abit IP35 Pro
Crucial Ballistix 8500
Corsair 620HX
Samsung SH-S203B
Seagate 400GB
WD 160GB
ATI X300

[Soulburner]

Did you try other slots than #4?

[Magic Chief]

Yes, I used all of them.