But everytime I build a new system...I take what is currently out and compare them. AMD came out the clear winner. Their dual core chips smoke equivalent Pentium chips.
As far as your question goes...you're going to have a speed difference between the 2 chips...doubling the L2 cache is certainly nice. $200 nice? That depends on your budget and the other components you decided on.
I originally wanted the AMD X2 4200 for like $300 or something. I instead got the 4800 for $600 because it will just last me so much longer than the cheaper one.