Whee, I just went from 545MB free space to 1.11GB free space on the Eee PC! I know that doesn't sound like much, but when you consider that this particular model only comes with 4GB total space, lots of which is take up by Windows XP, you'll see why I'm rejoicing. :)
And all I did was run CCleaner to get rid of unnecessary files, then go into properties and compress the C: drive to save space. I love when there's a quick, easy solution to issues that crop up.