I saw those things. Seemed like a good idea, so I went and spent $100 getting a new battery, a bigger hard drive, and a faster wifi card,....
For my IBM X24 Thinkpad.
Ok, it is a pound heaver, but it has a 12 inch screen, a lot better keyboard, and a Track Point. Even if I had just bought a clean X24 off eBay I would only have $300 into it. You Mac guys could pick up a 12 inch Powerbook for what one of those toy computers cost.
Graywolf's Law: New is only better than old when it is actually better and costs less.