Define good. They will multitask better than a single core but in many cases the dual cores are overall slower than an on par single version(with only one core speed). However overall you are future proofing yourself.
Incase my previous one takes too long to make sense of simply put the singles are better overall for speed but duals are futureproofing yourself. I would take the dual core as in the not so distant future you will get more from it as you sound as if you are a gamer.
I am no gamer but I would like my next computer to be faster, particularly multitasking. At the moment My dell Dimension 4300 (4 years old)can get swamped when I ask it to do too many things. I have upgraded RAM etc as far as the MB will take.