New windows 7 install freeze (memory issue?)

[Pyromk1]

Hello all
I've been coming to this site for years to fix my problems but now I think i may have a specific problem that i cant see answered already.
A while back I bought windows 7 and thought to upgrade to the 64 bit version from my 32bit XP so that I could expand my RAM. After a clean install I found that my PC was locking up randomly (sometimes at the splash screen and sometimes whilst on IE, but never it would seem on games) The mouse would keep working for a few seconds and then eventually that would stop responding too. ctl alt delete had no effect and I would have to switch the PC off at the back to reboot.
I took it into the local PC repair and they claimed it was the my graphics card, which I didn't think was likely but i by this point i just wanted my PC to work. windows 7 32bit installed with absolutely no problems and i've been running that for about 2 years now.
Now Ive upgraded my graphics card to an ATI HD 6870. I figured id give 64bit a shot again. Same thing is happening. now I know a little more about the way 32bit and 64bit work im thinking its a memory issue but im not really sure what to do to test it as DDR2 is expensive and i don't want to buy a whole load and discover its something else entirely.

Any thoughts would be very much appreciated as I'm getting tired of this PC just never doing quite what i want it to do

my spec is as follows using (cpu-z):
CPU: AMD PhenomX4 9500
Motherboard: ECS GF8100VM-M5 (nvidia nforce720a chipset)
GPU: VTX ATI Radeon HD 6870
Memory (expanded):
DIMM # 1
SMBus address 0x50
Memory type DDR2
Module format Regular UDIMM
Manufacturer (ID) Nanya Technology (7F7F7F0B00000000)
Size 2048 MBytes
Max bandwidth PC2-6400 (400 MHz)
Part number M2Y2G64TU8HD5B-AC
Serial number 01E91452
Manufacturing date Week 31/Year 09
Number of banks 2
Data width 64 bits
Correction None
Nominal Voltage 1.80 Volts
EPP no
XMP no
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 3.0-3-3-9-12 @ 200 MHz
JEDEC #2 4.0-4-4-12-16 @ 266 MHz
JEDEC #3 5.0-5-5-18-23 @ 400 MHz

DIMM # 2
SMBus address 0x51
Memory type DDR2
Module format Regular UDIMM
Manufacturer (ID) Nanya Technology (7F7F7F0B00000000)
Size 2048 MBytes
Max bandwidth PC2-6400 (400 MHz)
Part number M2Y2G64TU8HD5B-AC
Serial number 0E6E2525
Manufacturing date Week 02/Year 09
Number of banks 2
Data width 64 bits
Correction None
Nominal Voltage 1.80 Volts
EPP no
XMP no
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 3.0-3-3-9-12 @ 200 MHz
JEDEC #2 4.0-4-4-12-16 @ 266 MHz
JEDEC #3 5.0-5-5-18-23 @ 400 MHz

 

[soundguruman]

Did you reformat the drive entirely before making a clean install?
You MUST do that before installing 64 bit. 32 bit will not upgrade to 64 bit.
Are you SURE that you have a 64 bit motherboard and processor?
64 bit will NOT install on a 32 bit machine.
Look up the motherboard and processor specifications. VERIFY, do NOT assume.

There have also been FAKE copies of Windows 7 circulating, it looks just like the real thing.