I'm not saying there are huge benefits for dual cores yet, there are a
few small ones. And besides gaming many people say a dual (core) system
feels more responsive, and it is faster in multitasking

Add that to the fact that the 3000+ is a simple Athlon64 model and the
3800+ isn't and I would say that if the difference in money doesn't
matter you should take the X2 3800+

Marc