Please help - constant bsod with message system_service_exception and random crashes

[Balgruuf]

Also my computer is taking forever to boot up and to start most programs that usually start instantly. I've got a feeling that my hard drive is failing but I don't want to go out and replace it unless I know it's the problem.

Specs:

Intel i5 3570k @ 3.4ghz (stock)

Radeon 7950 3gb (tested with another gpu, and this is not the issue)

8gb 1333mhz ram (not sure on the make but it's kind of old, and I'm sure sure this isn't the problem)

1tb seagate barracuda - boot drive (this is the one that I think is failing)

3tb wd caviar green - storage

550w cooler master psu (could also be the issue)

Intel z77 mobo