The bad old northwoods are still fine, and can be overclocked. The 2.8c is especially good.
Here's a guide on LGA775 and new tech (by me):
http://forum.pcmech.com/showthread.php?t=104713
LGA 775 prescotts are supposedly beasts. The 3.4GHz one runs (supposedly) faster than an FX-51 and runs at 35C under load, leaving a lot of headroom. The one suggested by kram should be perfect for your current and future needs.
fedz