centrinos are often faster or at least as fast as pentiums. multiply a centrino clock speed by 1.6-1.8 in order to get an equivalent pentium speed.

centrinos are not significantly more expensive. shop around.

i'm not taking the time to look but i don't think 9400rpm drives even exist. regardless, check out barefeats.com & you'll see that in many instances 5400rpm laptop drives actually outperform 7200rpm drives. 7200 is nice but 5400 is plenty. if you run into track count/plug-in problems with a 5400 i would then instead recommend a 7200 firewire external. cheaper and a hell of a lot more storage for your $.

centrinos are consumer chips that use processing power for low level system stuff. not good for audio.

AMD chips kick ass, often much more so than pentiums. check out the "LIVE 4 PERFORMANCE TEST" thread in the Ableton forum for some really good, up to date info on this.

as far as upgrades, that 2ghz centrino chip is already faster than your 3ghz pentium out of the box. and the newer centrinos have a larger L2 cache.

everyone's comfortable with different things, but i would never buy a computer from a place "specicalizing" in audio machines. that's just marketing fluff that you pay more $ for. spend 20 minutes doing the things recommended at musicxp.net and you have a 'music optimized' machine... without paying luxury tax from one of these Specialists. bs.

if so desired, setting up a dual boot machine is also very simple. you can easily do it with the standard xp install discs or you can use something like Partition Magic and Boot Magic.