Well it really depends on what your doing and what Athlon 64 you plan on getting. But I would say in my personal opinion any Athlon 64 thats comparable to a Pentium D is better than the Pentium.
general rule of thumb that's pretty much held true since the dawn of the processor wars: AMD>Intel for gaming Intel>AMD for office applications and rendering (high end video/photo editing) There have of course been exceptions to this rule, but for the most part it's held true for many a year, and the current generation isn't really any different. With the release of Conroe Intel might upset the balance a bit, but for the moment decide how you wanna use your system and apply the above to determine which proc to go with. At the moment neither 64 bit nor dual core gives a significant boost, as there's almost no software on the consumer market that supports 64 bit computing or multi-threading, so neither processor is really showing its true strength, and before we see a serious push towards either to be honest the current gen hardware will most likely have been outdated significantly.
