I think he wants a cpu upgrade not a motherboard upgrade(if I understood it correctly).
btw thats some old hardware there, i don't know if you'll still find one anywhere. If it's your main rig, try building a new pc. It won't cost you allot but it will be much better than that 4200+. You can look into some APU's if you considering a new pc.
If it's your secondary rig, an bios update and maybe a Phenom X4 9350 might work, i'm not sure.