pinky you may want to be EXTREMLY cautios about what you do. I don't want to see you get banned, but man, multiple accounts is bad news. Before posting more you may want to report your claim in the CF Suggestions section as well as wait for a response from a mod or David. Just to be on the safe side.
As for your Dad's PC. Anything greater then what he has in it now will improve it. More RAM is better, a new video card is better. Anythgin will imporve it so long as it's better then what he has in it already. Will you notice a HUGE difference, possibly, but don't expect it to be anythign on par with a dual-core or anything. But yes, you will notice a difference.