KnoppMyth is the most popular such distro but MythBuntu is gaining steam. For my MythTV boxes I installed Ubuntu Server and then installed Myth, my video and capture card drivers, X, Ratpoison, and the w32 codecs. All in all it came to about 1.2 GiB. I used LVM to make a large virtual partition out of a horde of old IDE disks I had lying around.I seem to recall in the last edition of linux format there was a distro that installed everything you would need for a HTPC I will try to find it for you.