We got two Aspire Ones running Linux
and have been absolutely delighted. We used to take our 13" MacBooks everywhere, but now the Aspire Ones travel instead.
The Wife is happy with Linpus and Acer's consumer friendly front end, but I dropped Ubuntu's Netbook Remix on mine. All the hardware worked out of the box, it boots in one minute and no Microsoft software on it at all.
Best thing - we got two of the 8GB SSD, linux models for the same price we would have paid for of one XP 120GB models. I've never seen clearer evidence of the Microsoft tax.
These are very, very sweet - and economical - little computers. In fact we like them so much we're purchasing a third as it seems Acer is moving to the 10" screen.