nothing wrong with that mobo its still a good solid board. You have a good cpu no doubt about that. Do you have a pic of the zalman coz if its any one of the cnps95.... range it should be fine could maybe just need cleaning and reseating with some good thermal paste. Anyway I would go for these for a decent gaming boost and maybe a fresh install of your op system to speed up boot times
IF you could stretch your budget a bit further go for a 260gtx for an even bigger improvment in your games

IF you could stretch your budget a bit further go for a 260gtx for an even bigger improvment in your games