I am very lucky to purchase computers. I have a macbook, netbook, toshiba laptop (wife), and my trusty T61 thinkpad. I have realized that I use each device for a specific task. Excluding my wife’s laptop I have found that the macbook and netbook are interchangeable. The small form factor MacBook makes it as handy as the netbook.
Because of this I am thinking a purchase to replace both would be in order. A 13/14 inch laptop that I would use for more travel and development.
The Asus UL30 or the IBM Thinkpad Edge are pretty tempting.