Oh, btw, you can reduce the hash size.
There's a number that reads 1000 in the hash-section at the bottom. Basically it's how much resources (I'm not sure if it's CPU or Memory, or both) to give to any given hash. Anyway, if you decrease it, you increase checktimes but decrease stress on your machine.
Edit: "Its not a bad pc, 2.1 GHz Processor."
I've got 3.0 GHZ Intel, and it's what you'd call 'old'. Still I'm running a server AND playing C&C3. Your PC is bad, whatever specs you have.