Here's Eric bloggin about which Linux distribution to suggest to his friend who is to switch from Windows…Fedora, Suse, Debian or Slackware.
Read the overview of advantages/disadvantages for the average user here:
As a coffee mug I have says, “Different isn't always better, but better is always different”. Don't discount Linux because it isn't just like Windows. The truth is, the Windows interface leaves a lot to be desired, aside from the stability, performance and security issues that continually plague the platform. If you want a computer operating system that will let you get online, browse the web, write a document and listen to some music, you will find that Fedora or openSuSe more than meets your needs and is no harder to use for those tasks than Microsoft is. More over, it's free to use, it doesn't crash, it's secure and it performs better than Windows on the same hardware. If you want a machine that performs well, is easy to update, has rock solid stability and can grow with you as you expand your knowledge of computers, then go with Debian.