Microsoft won't guarantee that it will run most of the hundreds of thousands of Windows programs. The company won't even promise support for Office, perhaps the most ubiquitous of Windows programs. Office and other business software will be able to be run off a server and viewed on Eiger-based PCs using Microsoft's remote desktop software or thin client software from Citrix and others.
So here we have it, the fat, thin client thingy. It's being billed as a 'bridge product' for corporate customers who can't afford Windows XP right now, but want to integrate all of their machines into standardized security framework. Sounds fine, but the name is wrong. I think it shoud be called a 'dam product', because it seems to be an effort to keep those desktop from falling into the thin client world. Brian Madden has a nice short writeup on this. If they would concentrate on resolving the virtual client licensing problems for software and fully switch over, maybe we would all be better off.