Rolli59 is correct. I finally found some time to dig a little deeper and found some info. Processors for the 939 socket type were only produced between the years 2004 and 2006, thus you're not going to see blazing fast quad cores. The Opteron 185 and Athlon 64 FX-60 were the fastest processors produced for it, both being dual cores clocked at 2.6 Ghz. Both of these processors seem quite hard to come by, however I came across an FX-60, but at a price of $197. That of course would be a ridiculous price to pay for a .4 Ghz improvement. I could easily overclock to that for goodness sakes, which is what I'm sure I will end up doing since I cannot afford a mobo+ processor upgrade and all that comes with it. Thank you rolli59 for the direct and usefull answer.
Edit: I somehow missed malmental's comment till just now, thanks to him as well