Tinuva
The Magician
Linux Mint XFCe
or
Windows 7
My wife has a Lenovo Ideapad S10e with a 1.6 Atom CPU and 512 MB ram and she's running Windows 7 smoothly, it came out with Windows XP and she tried Linux Mint for a while, but didn't like it (I actually thought it was great). So I had to install something else and tried Windows 7, to my surprise it worked great.
And another one didn't read the thread.