Doesn't look like any of us right now will make the 'recommend' specs for Longhorn. But then again we might have double the specs by the time its released.
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.
Read more here.