what, is an os out for demo or something? or are you talking about when it first comes out? i know longhorn doesn't come out untill 06 and don't forget about how it may be held back. i say get an xp now and upgrade after it's been out for a while(give or take a year or 6 months)to get the bugs fixed and that stuff, who knows, maybe intel will come out with a better 64bit cpu or some thing along those lines. i think it would be better to wait. also, it depends on how much money you are willing to shell out. people talk about the best cpu's but it realy comes down to two factors 1.how much money you have and 2. what you are going to use it for. just take all those factors in mind and you'll do good.
ps. sorry for such a long post tee hee hee.