What kind of PC will be needed to run Longhorn?

What kind of PC will be able to run the new version of Windows, codenamed Longhorn? During last year's Windows Hardware Engineering Conference, Microsoft claimed that the "average" PC running the new OS could have something along the lines of a dual-core CPU running at 4 to 6GHz; a minimum of 2GB of RAM; up to a terabyte of storage; a 1GB 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". However, there was really never any solid confirmation of these specs, and we were left really wondering just what sort of machine Longhorn would expect. An even better question was just when the hell was Longhorn ever going to be released anyway?

According to a new whitepaper issued at the latest WinHEC by Microsoft, the new OS will instead find itself running on a machine with "a modern CPU", 512MB of memory, and a "graphics component with a Longhorn display driver model (LDDM)". Microsoft also claims in the paper that "Longhorn will run fine" on 256MB systems but believes that "512MB or more of RAM provides really good multitasking performance". Evidently, Longhorn has turned out to not be quite the beast everyone thought it was. Perhaps some more demanding technologies have been shelved until Blackcomb, the new generation OS after Longhorn. Or perhaps Microsoft just "performance tuned" everything. Hmmm. Anyway, the real question I am left with is... what exactly is a "modern CPU?" 900 MHz Duron? Or dual-core Athlon?