3DAvenue posted a review of the AMD Athlon 64 X2 4200+ and 4800+ processors.

Gone are the days where a SMP system requires you to buy two (usually identical) processors, each with their own cooling requirements. Dual Core eliminates this by simply living up to its name - one processor has two physical cores rather than one, and while at the present time a X2 processor from AMD does indeed seem to cost twice as much as a standard Athlon64 of similar single core power, in due time the fact Dual Core eliminates the need to use two sets of pin configurations and other processor material will drive SMP system costs down even further. If there ever was a time where SMP systems would develop into a standard in the PC world, this is it, providing both AMD and Intel continue to drive these products.

AMD X2 4200+ and 4800+