What's the current best buy for an AMD chip?

I’m looking at a 4200+ (Manchester); 355 @ newegg. Is this a good choice?

Relative to what?

I always just check anandtech’s cpu price guides, then i check their realtime pricing database:

I don’t know if it’s the current best buy (bang for dollar) out there, but it’s what I got a couple weeks ago and I’m very happy with it.

4200+ is a good deal. I suggest you go here:
http://www.mikeshardware.co.uk/CPUPricesAMD.htm
…for a complete (official) price and spec chart of all the CPUs. He has one for Intel, too, but they won’t be in the running until midsummer.

The 939 pin dual core Opterons were pretty popular last I checked. Costing about the same as the equivalently clocked X2s with twice the cache.