I'm a fan of overclocking.
Buying a cheap CPU and then running it way out of spec to make it perform similar to a much more expensive chip.
Current chips I'm using:
Q9550 @ 3.4 GHz
E5200 @ 3.75 GHz
E2180 @ 2.66 GHz
Intel E2220
3200 MHz (8x 400MHz)
1.360v
63C under full load.
Arctic Cooling Freezer Pro 7
http://valid.x86-secret.com/show_oc.php?id=369469
5.8 Vista CPU score