Hello and welcome to the forums
If your only choice is between those CPUs then,
None of those will give you a noticeable boost in almost every game,but since you already have a dual core CPU,then i would recommend going with Q9400 and OC it,however in games which aren't multi-threaded the performance would be the same(i am comparing them by having same clocks),but in games that benefit from multi-core CPU,it will give you a boost in games.
But IMO,if you can,then don't upgrade now,since socket 775 is out of production.
Build a new system with an i5/i7 or AMD Phenom II CPUs instead and they will give you more boost in games.
not really have in any major performance problems but do notice on a few of the new fps games like metro2033, bf2bc i get a lot of lag and slow down some time i never run me games with FSAA or anti scope filtering if i have to i knock em down to 1 and generaly run at 1024x 768 or 1280x1024 seems to get better at medium setting in the games but i would have throught i could get away with high thats why i think my cpu could be a bottle neck hopefully its not my gfx card gtx 260 oc have had w7 on my system had so many probs with games on it so now the disk is just sitting here in the pack.
weres the best place to find them 2nd hand cpus? ebay seems to be ??££££££
so you would still say its best to go for a slower x4 core than a fast x2 core? my board will take the q6600 but thats about it want to hold off i core for now
First of all,Metro 2033 is poorly optimized,even more powerful setups don't get good FPS in it.
But its strange that your FPS isn't high in BC2,because a GTX 260 can handle it fine on 1280x1024,have you updated your VGA driver?