Whoa, epic irony...
Regarding PVR functionality for OTA broadcasts...
I really cannot comment on Linux (I have heard of MythTV), but a Mac Mini platform running OSX and EyeTV suck for a variety of reasons. The most problematic is a known issue that OSX cannot handle being plugged into the AV receiver via HDMI in an "always-on" scenario (check avsforum.com in the mac htpc section)
Now install Windows (version of your choice) on that Mac Mini and install/run Windows Media Center and everything works perfectly. The UI is great. The setup is great. Then you can install the following programs side-by-side with WMC to complete an awesome HTPC experience.
- SABnzbd - to download NZB files
- CouchPotato - to manage movie NZB files and feed them to SABnzbd
- NZBDrone - to manage TV series NZB files and feed them to SABnzbd (NZBDrone is a windows only counterpart to SickBeard)
And, while not unique to Windows, it's nice to know that the browser experience on Windows does support (as one would expect):