This is an updated post since the Windows Port of Myth TV is NOW WORKING!! This is still not for the faint of heart, as there does not appear to be an installer, and so you have to follow the directions, on compiling the software using MinGW, and have to install perl as well. For those that don’t have the guts for this then WinMyth is for you !!
You still need to have a computer that has a TV card installed, and in every case you need to install some kind of codec that provides the compression and decompression of the TV video stream, but things are really looking up. Soon every one who views over the airwaves will be able to have a DVR in their house!!
I have recently learned about 2 alternatives to mythTV and they are MediaPortal which is open source, and GB-PVR, whose license according to the Wiki may be LGPL, but for now is closed source. So have fun working with your computer as a Personal Video Recorder (PVR), but I actually prefer the term Digital Video Recorder (DVR).