I'm not a Linux-head but I recently downloaded Cygwin. It's a UNIX port that runs directly under Windows and doesn't require any special disk partitioning, dual booting, etc.
It may be an effective way for people to try out Linux before they commit time and energy into repartitioning their PC.
Cygwin is free from
www.cygwin.com. You can run KDE (3.x beta) as well:
http://kde-cygwin.sourceforge.net/
I followed the install docs for Cygwin and KDE-Cygwin and they installed painlessly and worked on first run. It's running under Windows XP Pro with NTFS volumes.
Check it out.