Computer hanging up on me

Hey guys. I noticed about a week or so ago my computer started hanging up when doing normal tasks ( closing windows, opening applications). It hangs up for about 5-10 seconds. I also notice my chipset fan is running somewhat louder then normal ( not sure if this is related to the issue or not). Any ideas on what my problem is? I was going to run to the store and getting a dust cleaner to clean all the fans inside the computer , but im not sure if that would help at all.

evga nforce 750i sli ftw mobo
intel core 2 qaud q6600
2x 2gb(4g) ocz fatality ddr2 1066mhz
2x xfx geforce 9800gt
750 watt ps
vista 64 bit ultimate

nope, not getting any errors at all. ill try memtest now.So its most likely the ram that would cause that too happen?

I opened up one side on my computer in hopes i could maybe hear or tell what would be causing this. It seems whenever i get a hang up, either my chipset fan or processor fan runs very loud and then quiets again when the hang up stops. Im not sure if replacing these fans with better aftermarket fans would solve my issue. Any ideas?

My chipset fan and processor fan seem to run quite hot ( especially when gaming). Would buying new fans help this issue? or does anyone have any advice on what to do?

82 is on the high side but the ones I worry about are mainly CPU and GPU.... How can you be sure PCWizard is accurate? 40 is good, 69 is really high if its an idle temp but slightly high for under load. Cooling things down might help. What kind of case is this rig in? Antec 300 is a cheap well vented case if you're looking for a low budget solution.

I agree with rberry too, there could be a lot going on here. Defrag the drive(s), run a antivirus scan. DO NOT waste money on one of those registry cleaners! Those are for suckers.

As far as I know, usually with thermal events the PC doesn't hang/freeze up, it just shuts off like a kill-switch (of course I could be wrong). That's why I suspect a hardware failure that is building over time or software corruption (it IS Windows after all). I had something similar that ended up being a bad stick of RAM.