Anyone who thinks OSX is bloated should read this:
Microsoft is expected to recommend that the “average” Longhorn PC feature a dual-core CPU running at 4 to 6GHz; a minimum of 2 gigs of RAM; up to a terabyte of storage; a 1 Gbit, built-in, Ethernet-wired port and an 802.11g wireless link; and a graphics processor that runs three times faster than those on the market today.
Is that really that unreasonable? Sure, if they released it today, no one could use it. Aside from the fact that it isn't finished yet, it's still a good two years out, at a minimum (the optimistic estimates for a release dates that I've heard are 2006). Think about the standard PC back in 2002, and compare that to the computer of today. I think that the specs you list above would be reasonable in 2-3 years.
That spec is just wrong: it's actually the slide that Gates used at PDC last year to illustrate what the average pc might like like in 2006, and actually nothing to do with requirements for Longhorn.