I have a boring "regular" Barton 2500+ where my max stable 24/7 overclock is approx. 2350MHz. If one can reliably get 2600MHz with a mobile Barton, then I'm sure that would close the gap.
I get temped by the mobile Bartons, but I already have one too many nForce2 motherboards and two too many XP 2100+ cpus. If I picked up a mobile Barton, then I'd end up with one too many Bartons... I have extra memory, chipset coolers, and so on. What on earth do all you regular upgraders do with all your "old" equip? I only have use for so many computers, and I seem to like to doink around with the shiny new stuff as it comes out.
Anyway, what I like about the A64 is that it runs super cool and, as has been mentioned many times, is great for gaming. I also do a lot of quantitive/science/geeky computing, and for those applications I really like the performance of the A64 in both 32-bit Windows and 64-bit Linux. For example, I have some metacode that runs on a statistics package (R) that takes over 15 minutes per run on my Barton and about 1 3/4 minutes on my A64. I run apps like that many times each day, and the time savings is significant. I have plans for more whacky, monster data blasting apps, but I will likely move on to a multi-processor workstation (that will be a "work" computer unless I fail to acquire the needed funds).