Ultra-Mobile PC - Go Everywhere. Do Everything [Yahoo! Music Unlimited observation]: "Featuring full Microsoft Windows XP functionality and the ability to touch, write, or type, the Ultra-Mobile PC is a powerful companion that lets you communicate, accomplish your tasks, and stay entertained and informed wherever life takes you."
Another good reason to consider Microsoft's Ultra-Mobile PC (code-named "Origami"): I recently received an email notification from Yahoo! explaining that the price of an annual subscription to Yahoo! Music Unlimited will ~double (from $59.88 to $119.88) if I want to have the "To Go" option -- i.e., to be able to use subscription-based music (i.e., albums I have downloaded but haven't purchased) on non-PC devices. I assume an Ultra-Mobile PC would appear to Yahoo! Music Unlimited as just another PC, so I'd likely to be able to save ~$60/year (unless Yahoo! is going to change that part of the service license as well; at the moment, I can have music on up to three devices). For now, in any case, I'm going to drop the "To Go" option, as it's a nuisance to use subscription-based music on my portable device (A Creative Zen Micro) -- the user experience leaves much to be desired -- and not worth the extra cost.