The CPU by itself may be fast nor nonfast. It depends on the chipset and the motherboard design.
For myself I use an ASUS motherboard and the KT400 chipset with the AMD processor.
It’s pretty damn fast for me!
And the front side bus, and the hard drive set up and a dozen other things including how bloated you've let Windows and its registry get. Most people would see a much better performance increase adding an extra hard drive and running a two drive Raid 0 array (if the motherboard is set up for it) than by upgrading a one or two year old chip. (Also stay far away from ANY software which has the word "NORTON" on the box)