A linux distro (distribution) is a complete, installable operating system based around the Linux Kernel.
There are one or two that are especially good for dedicated MythTV boxes (the kind you'd have on a HiFi stand in the lounge), others are especially suited for use as workstation PCs.
Here's an alphabetic list...
Debian is a widespread distribution, Debian has a huge community and is probably the most 'free' and socially driven distribution - an excellent choice and MythTV is well supported. There are a couple of guides:
- Mythtv Installation Guide for Debian
- Debian Guide
- Another Debian Guide
- Ubuntu Installation - A step-by-step guide for setting up MythTV on Ubuntu
Fedora is a very popular distro - especially well supported by the famous Jarod's Guide. Some work is also being done to write a single "kickstart" script based from Jarod's Guide. You can find this script at 
There is also the Fedora Core2 Guide
FreeBSD - Stacey Son has provided a FreeBSD port of MythTV
Gentoo - If you are scared of command prompts, Gentoo is not for you. On the other hand it is extremely well documented in the Gentoo Handbook. Also each install is optimized to your processor and highly more customizable than other distros are Binary. Gentoo guides:
Official Gentoo Guide:(currently Incomplete)
Knopp Myth is probably the easiest way to install MythTV. After all - that's what it was made to do. It's mainly oriented towards dedicated Myth boxes (though of course it runs a complete GNU/Linux OS so no worries about serving music or other files). Insert the CD into a 'blank' PC and you'll be running Myth after a few minutes. It's Debian based and, as a special trick, MythFrontend will run from the CD without installing. (Also see the Knopp Myth page).
- There's also the Setting up MythTV under Mandrake 10.1 Guide
- The MythTV How-To wikibook uses Mandrake as an example
Mini Myth boots over a network and runs Myth Frontend on diskless Via EPIA M systems. (ie you need another 'proper' machine too!) This is great for 'satellite' systems - like having one in the bedroom or kitchen...
Red Hat 9
Slackware is one of the eldest linux distributions and still going strong. Historically often used for servers. Some of the MythTv users use this for both backend as well as frontend purposes.
Suse, A Popular distro in Europe and the US. Known for it's Yast Installer and it's Ingenuous Graphical boot Screen. The company was resently purchased by Novell.
- How To Suse 8.2 Howto
- How To Suse 9.1 Howto
- Suse 9.2 Howto
- Suse 9.3 Howto
- Another Suse Howto (9.3) (stil a work in progress)
- Suse 9.3 from YaST and RPM Howto
XBox-linux - With this distro you can run Myth Frontend on your Xbox (ie you need another 'proper' machine too!). As you can guess from it's other name - Xebian - it too is Debian based - you need to know that if you follow the MythTv Xbox guide. Alternatively there is another XboX Guide.