Windows 7 stuttering in games (mainly valve)

mainly valve cause thats all i really play. ok well ive had this problem before and i had fixed it, came down to it being my caviar green 1tb drive, then went out and got a caviar black 1tb, and that had fixed it for a while. now its sort of back. this time it happens once in a blue moon. and does it weirder than ever. this might end up being a long read but i want to get this out of my life once and for all.

Well before i changed drives i have done multiple testing when i had the caviar green in, and i tryed disabling both my sound cards (on board, and regular sound card), my nvidia drivers were up to date. uninstalled my virus protection. then when i got my new drive i reformatted and everything was working fine (went with older drivers on my nvidia card cause people were complaining about the 19x drivers) but seem to go weird on me again when i installed my ant virus again, which is nod32 smart security 4 (only using the trial for now) haven't uninstalled it again im trying to get it stutter constantly so maybe i can uninstall it and see. but this time it had done it while i was watching 1 of my shows the whole video froze while the sound was still going then came back, that never happen on when it was doing it to me before my reformat and my old drive.
also once in tf2 it also had froze like that, where thee audio was still going but the video was stuck. but its main problem is that it freezes for a sec and the audio loops for a sec, only thing is its not constant like it used to be. It used to be once every 10 to 15 mins and the micro stutter would last for no more than a second. now this happens every hour or more or just randomly. i am now wondering if it is my externals cause sometimes they get accessed out of no where, but then i did my own testing while i was in game un plugging both of them and then plugging them back in. next thing im going to try is if it happens again or when it happens again uninstalling nod32, maybe that is accessing something while im in game and making something spin up, or waking all 3 drives up at the same time (since i still have my caviar green 1tb installed but now used as storage)

Im really stumpt and this thing is so annoying i cant even enjoy a game, instead im really focused on the screen waiting for it to stutter and trying to notice things around me. my temps are fine as to when it used to happen i would alt tab and have cpu z open and check to see if anything was over heated.

also to wondering if this could be a problem in tf2 i get close to 300 frames, but on some maps like the mid area it will drop to as low as 80 i was wondering if that giant of a drop would have any effect.

im just hoping its some sort of driver issue and not hardware, i have not updated my bios as to last time i thought that what may have caused the problem. im just running out of ideas people. I love windows 7 to much and im willing to stick it out of this is a problem and just wait for an update, but what is killing me that is it might not be an update it might be hardware. thank you for your time and sorry for the long read

it make me feel a tid bit better if we can single out the cpu and say that's not it. this pc is no more than a week or 2 old that's what boggles me, my old rig was perfect but then again it was on xp.

intel i7 920 (1366)
asus p6t (mobo)
caviar black 1tb
caviar gren 1tb
western digital external 1tb (my book)
western digitial external 500gb (my book)
ocz gold 6 gig ram (1600 mhz)
corsair 750w psu
asus xonar d2 sound card
windows 7 x64bit professional

The rest of last night it didnt stutter at all, but it almost looked like it wanted to, now im wondering is 7 doing something in the background while im gaming that is accessing random things?

nothing at all? i guess it must be a hardware problem...

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