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For any computer chip that is 2400+ (2.4 GHz) or faster, the race is neck and neck between Intel and AMD. They will perform about the same and cost about the same. Just look at PhoenixOfWater's pricing of similar performing computers: $655 and $642. You'll be happy with either one. For CPUs that are slower, AMD is by far cheaper, so go with AMD.
Things to consider if you want to buy really soon:
1) AMD will release Barton most likely on Monday. It will have double the cache, and thus perform a few % better than the current Athlon chips. We are quite interested in seeing reviews. They might finally have something that can compete with Intel's top chip, the 3.06 GHz P4.
2) Intel won't likely have any new chips until mid March. If you can wait until then, you'll likely see hyperthreading (better performance when running more than one program - like virus software and a game for example) on most of its chips. Possibly a 3.2 GHz P4 will be out then as well.
3) Intel will slash prices on its chips by $50 each (except the very low end of course) on Feb 23. Amd will likely follow suit. Intel will have a major price cut late March.
For those 3 reasons, if I were to buy a computer, I'd really think now is the worst possible time. If you can wait 2.5 weeks, you'll get something much nicer or much cheaper.