I should probably mention that I largely use my PC for gaming and a bullet point spec would be:
GeForce 7800 GTX 512MB x2 (SLI'ed)
You probably will have to look at the 2006 charts for a comparison.
As to the FX60, I can overclock mine to 3.1 ghz, but they vary in overclocks between 2.8 and 3.2 ghz. The main thing I'd change on your machine is the graphics cards. A new 8800 GT512 or 8800 GTS 512, or an ATI 3870 if you want, would make a world of difference in gameplay. I can run Crysis on my FX60 machine with the 8800 GTS 640, so I think your 939 should be able to run well for another year.
2 gb ram is plenty for a 32 bit OS and easier to OC... the video card upgrade may be a good option. I have mine at 3.0 ghz with an OC'd 8800 GTS 640 and it is more than competitive at present. Benchmarks at A64 x2 6000+ levels. 3dmarks06 at 10,083. Make sure you have a good aftermarket cooler because the FX60 is a space heater!