Which processor is good in performance because the comparison shows Core2Duo is more costly comparing to Core2Quad. Is this mean Core2Duo is more higher in performance than Core2Quad?
The prices you see today are simply the result of marketing forces (supply and demand) and nothing to do with performance. The Core 2 Quad is easily the better performer.
I agree with Al. Don't waste your money on stuff this old. That's just throwing good money for bad. Purchase something far newer; your performance will be significantly better and your power budget far lower.