Game Stuttering Issues on Vista?

Ok ive been playing games like Dragon Age Origins and Company of Heroes. These games stuttered alot at some point but have very smooth FPS (Like 45 and drops to 3 or 5, in or out of battles and intense stuff) and reverts back to a very smooth gameplay again)like intervals.This happens continuously not only in these two games but EndWar, Dawn Of War 2 and some other games as well. I have the latest drivers. i was thinking it was the temprature of my videocard which is in 45 degrees in full load. But that temp is not even near the temprature in which it can act insane!I also thought it was Vista since ive visited forums stating that Vista was the cause for game stutters. Some games that i didnt experience the stuttering was Crysis and ETW.And note that my games are patched up.Everything i tried to fix the problem failed so far..Please Help!!|||your vid card may be having a tough time with the settings your playing at try lowering the res for those demanding games. or maybe go sli or xfire

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