Emulate the OLPC or Eee PC operating systems in Ubuntu
Tom Hoffman has posted some pretty simple instructions for running the OLPC's Sugar OS on Ubuntu. Essentially all you need to do is add a repository to your sources.list and install the Sugar emulator. Odds are the display will be too large for your laptop, but you can follow these instructions for changing the resolution.
There are a few more steps involved in getting the Eee PC interface to run on Ubuntu. First off, you'll probably want to have a copy of the DVD that came with the Eee PC, (which sort of defeats the purpose of trying before you buy, but if you've already got an Eee PC you can safely emulate your desktop environment for experimentation purposes). But Asus has posted most of the source files for the Eee PC on its ftp site, so there might be a way to get build the operating system in emulation mode without that disc.
If you're a little more adventurous (and if you read French), it looks like it's also possible to get the Eee PC interface running in Windows using Microsoft Virtual PC software.