x64 processors offer minimal improvements on microsoft platform as minimal applications have been compiled specifically to take advantages of the x64 enviroment and untill this point minimal gains will be made from just having a x64 OS and the belief that x64 Operating System is ALWAYS faster its simply not true.

Similar to the belief that with memory most people believe DDR2 is lower latency than DDR which is often not the case as DDR can usually embrace more agressive ram timings than DDR2 in many situations, its just the improved bandwith capability of DDR2 which overcomes this and sees the improvements.

Each processor stated here has good and bad points without discussing or understanding the difference in architecture its wrong to GUARANTEE one is faster or better than another, no processor endless scope for overclocking and if this is the goal some of the suggestions are poor

Ive been in the clocking scence for over 13 years and am a moderator on the largest overclocking forum on the net, but lets face it who needs to overclock these days, most current mid range PC's are very capable

Go with the Athlon X2 imho... good solid processor