From Linux.com:

With Linux appearing more frequently in the press and on TV, people are becoming more curious about it. They are still reluctant to leave their comfortable Windows world, but they are curious. Enter LiveCD Linux -- a CD with a full Linux operating system that runs completely from the CD without the need to install anything on the hard drive. Taking ten people who never used Linux before and who have only basic computer skills, I set out to run several LiveCDs through some informal tests.

Read the full thing here

MandrakeMove does fairly well, and so does Slax - my current personal favourite.