If it's that bogged down, why not take the opportunity to back your vital data and perform a system restore? With most OEM computers, it's no more than an hour then you're back and running. I find that always fixes things, as opposed to finding more programs that usually do mediocre jobs at speeding up your computer.
Or like Turbo said, invest in an SSD. But I think with your particular setup, you should go back to system default, the clone it over to the SSD. You won't regret it.
