that motherboard is socket 939, u arent gonna be able to upgrade to something worthwhile, u might want to upgrade to the latest intel sandy bridge plateform
2500K 215$ mobo=around 130$ and 4 gigs of ddr3=around 65$
for under 400$ u can get urself a more powerful pc, and btw id upgrade the videocard to a 5770 which u can get for under 130$ on newegg