Intel Core 2 Duo E6320

THE GOOD:
Price/performance, good overclocker, less than $200, 4MB cache. Runs so cool that often the fan on the CPU cooler isn't even ON.

THE BAD:
Intel is a large corporation, it's better to support smaller corporations and encourage competition. If Intel hadn't had AMD kick their ass with the Athlon 64, they wouldn't have bothered to make a CPU as good as this one (at least not as soon as they did).

SUMMARY:
Not worth upgrading to this if you already have a Core Duo, but if you do need a new PC this CPU is probably one of your best options. It's a little early to go with Quad-core, hold of on that for another year or two (depending on your situation, some few people will benefit from as many cores as they can get).