Constant non responsive progames PLS help

[terribleteee]

I've had windows 7 64 bit home premium installed for about a week and from the very start I've been getting non responsive programs. Everything from solitare to firfox to control panel to the system directory windows to far cry 2 about the only program that runs right is modern warfare. when they lock up the cpu will drop down to about 2% per cor. In previous systems this would only happen when when I maxed out the cpu. I'm stumped I've been trying to learn fast but I'm still quite the newb.
I thought the system would be good for a 64 bit os and I went with windows 7 because of the reviews i'd read. If this is a windows 7 based problem does anyone think It'll be resolved with updates? Or could it be a hardware compatability issue? It's getting frustrating I can't even navigate through 4 web pages sometimes and most games will lock up a five to thirty minutes in. I've been downloading and installing a lot of software as well but I'm always careful about the virus scans. I'd appreciate anybody's input.

Here are my hardware specs if anybodys got some ideas.
msi 790fx-gd70 MOBO
amd phenom II 965
4gb patriot viper II ddr3 pc16000 2000mhz
X2 xfx ati hd4890 1gb
rocketfish 900w pcu
1.5tb wd caviar green (os)
1tb wd caviar green (storage

 

[Zoron]

You've installed all the latest drivers?

 

[The_Prophecy]

Might also want to check your temps... CPU, Mobo, Hard drives... everything.