Check the manufacturer name and model, hen go to their website and look at the processor support list. That's the easiest way. But I very much doubt if you can still buy S939 processors. Even AM2's are pretty much retired now.
Yes the FZ60 @ 2.6 was the fastest and was produced under a 90nm process with 2 X 1Mb L2 cache ... hard to get but ideal with the unlocked mult.
They and the 4800 will do 3Ghz with decent cooling, and at that speed are about as quick as an E6600 Conroe Core2 65nm cpu ... roughly.
I can suggest getting a 2.2Ghz 4400+ which also has the 2 X 1Mb cache and you can push this to a 220Mhz FSB easily, giving you the evivalent to a 4800+ much cheaper ... odds are you won't even have to drop the HT ratio to get it there.
I suggest a better cooler - like a decent heatpipe tower unit.
You should be able to get one from e-bay.
The 4400, 4800 and FX all have the bigger cache.
The 4200 and 4600 have a 2 X 512K cache but run at the same frequency.
I hope this helps.
I'd rather forget the 939 era as the advent of the faster AM2 chips on the 940 platform really pi$$ed a lot of us enthusiasts off.
/waits for TC to enter stage left with significant bluster !!!