Quote from fm87
For an AMD CPU you need an AM3 or AM3+ socket motherboard.
For an i3/i5/i7 you need an LGA socket 1155 motherboard.
For your current processor, assuming it's a normal C2Duo you would need an LGA 775 socket mobo, of course LGA 775 stuff is expensive as all hell usually, and you would be better off just getting a new mobo/CPU which it seems you already decided.
Might not hurt to get a new PSU as well.
Actually, when I put in the new GTX 560, I also had to get a new PSU, I got a 700 watt one, should be sufficient.