I finally got a Core 2 Duo E6750 to replace my Pentium D 945 and what a performance increase this thing is fast, I haven't tried it on any games yet but 3D Mark and general PC use has improved so much. here is the installation process in pics and updated pics of my PC. I got the E6750 for £120 ($240) inc postage, which is pretty good price for the UK, but the best part is that my old Pentium D 945 is still worth allot on ebay I can get about £70 for it now.

Here is the rest of my PC setup:

Core 2 Duo E6750
ASUS P5N32-E Sli 680i
7900GS 256mb @ 618mhz/800Mhz
2GB Corsair XMS2 800Mhz ram
Hitachi 250GB SATA2 HD

The nice box the proccessor came in, it had a heatsink included but I used my Artic Cooler 7 pro instead.

Here is the E6750 its self doesn't look any different to any other Intel CPU

Here is the Artic Cooler without the fan just about to be removed

Ok so now the heatsink has gone we can see the old Pentium D 945 covered in Artic silver thermal paste

So now the Pentium D is out, the motherboard is ready for the new Core 2 Duo

so the Core 2 Duo E6750 is in and the heatsink is back on lets see what this thing can do

here are the 3D mark scores no over clocking the CPU in this test only the Graphics have been overclocked

Pentium D 945 scores
GPU @ 618Mhz core and 800Mhz Mem
CPU @ factory clock 3400Mhz

Score: 5212
SM2.0: 2186
HDR/SM3: 2152
CPU: 1709

Core 2 Duo E6750 Scores
GPU @ 618Mhz core and 800Mhz Mem
CPU @ factory clock 2.67Ghz

Score: 5517
SM2.0: 2200
HDR/SM3:2155
CPU: 2391

And here are some pics of the PC in action wiring needs some work