Upgrading PC for gaming

Hi there, new to forums and am looking for advice on my pc specs. I have a bit of money to upgrade parts but not enough for a new PC since I already have a laptop for everyday use. The pc will be used ONLY for Diablo 3, starcraft 2 and maybe any related games. Guild wars 2? Anyways,
Core 2 duo e6600
Intel junk mobo (can't oc, ddr2, pci-e 1)
3gb ddr2 ram
Gtx 250 oc
350w cheap psu
160gb 7200rpm hd

I am wondering where to start. My friend is willing to sell me his old amd x4 955 and new mobo with it (MSI 870A fuzion) for very cheap but could that money be spent in a better place?
Was thinking of going with 6-8gb of ram.
A bigger 500-600 name brand psu
Where else should I be upgrading, will the gtx250 handle any of those games decently?
Using a 42" tv via vga until I can get new 24" monitor
Advice please and thanks