Are you using any version of Linux on one of your systems at the moment? And if so what Distro of Linux are you using? and on what platform are you running it?
Also what are you using it for? Gaming? Server? Main OS? Or just to mess around with it and see what you can do?
For me, at the moment I have Fedora Core 5 installed on one of my systems, setup to dual boot with Windows XP. I use this for messing around with the OS, to test out some of the Emulators available for Linux, and to try out some of the other software available, and to generally learn about the OS as I use it.
I also had SUSE 10 installed for a while but not at the moment. I quite liked SUSE and it was easier to setup that most other Distros, and comes with a lot of software, as does Fedora.