Tux I've been using Linux for a very long time. I even made my way to linuxworld expo in 1998. The various flavors of Linux come in handy. Once you know what you're doing, Linux is usually far less frustrating than windows.

My Favorites

Ubuntu Linux - My current favorite desktop installation. I actually make use of it on one of my home servers too. It's pretty easy to manage. It does all of its post installation configuration after the first boot, so you can install it on a drive with any machine, then put the drive in the destination box (like a toughbook without a CD drive.
Devil Linux - One of my favorite firewall disttributions. It runs from a CD, and stores its config on a floppy drive, hard drive, usb key or whatever you've got. It's very solid and friendly to older hardware.
You can (relatively) easily build a custom dristribution of Devil. If you're a decent admin, you should be able to add your own packages as well.