If you can find a quad core 9500 phenom I, it might work. Your board is limited to 89-95w cpus; I recommend you change boards to am3+ and upgrade to ddr3. Either the 965 phenom II or the 4100 will work fine; check the cpu support list and bios file requirements before you order.
My main concern is that I meet the following qualification that is set forth by the company that I am looking at applying at for a work at home job. The following is what they say I need at a minimum for a processor.
3.0 GHZ Processor (minimum of a Pentium 4 processor or equivalent processor running at a clock speed of 3.0 GHZ)
I may be wrong, but I don't think that my current processor would meet that qualification.
I'm more familiar with the Intel processors than the AMD processors and that is why I am asking. If I need to upgrade my board, then I'll do that, but due to serious financial restrictions I'm looking at trying to use the board that I currently have until I get more money coming in to truly support a full system upgrade.
The phenom I 9500 won't run at 3.0 unless you overclock it. If you are currently using ddr2, you may find a core2 duo board/cpu in your price range, but most of those don't run at 3.0 either, but they're still faster than the old p4 smithville cpus due to their more advanced design. You may be able to overclock some core2 duos depending on the motherboard bios options. Good luck.