Looks like your board supports a number of the Athlon II parts, which would probably be the best/least expensive upgrades for your situation. The 9750 x4 really isn't gonna be as much of an increase as you really want, not worth the money in general. The higher clocked Athlon II dual cores are good. They don't list the higher clocked Athlon II x4's for some reason, but they DO list that it can take a 125W TDP athlon 64FX, so I don't know what the issue is with the quad core Athlon IIs.
Overall, I would look for a reasonably high-clocked Athlon II or Phenom II processor that is on that list to go with as they will be the best upgrades you can get with your current MOBO.
It looks like I found an AMD Athlon 64 x2 6000+ that is the same exact model that fits my motherboard, it is an 89w windsor f3 socket am2 (a bit older)...nevertheless, from the looks of it, it performs better than my 5200+ anyway because of the frequency. so I guess I will go with that...and I will emphasize that my motherboard absolutely does NOT overclock anything at all, and since I will be running at stock always, 3ghz stock may be appropriate. Running any quad core on this mobo would confine me to stock also, of which no phenom or phenom II socket am2/am2+ even reaches the speed of 3.0ghz.
Yes, I play games, but I won't be playing games that require a quad core (like GTA IV) anytime soon...but I will be playing Assasin's Creed II, which actually recommends the 6000+. Thank you all, thank you Moricon for pointing me to the website.