The other issue with an HTPC is that you don't have the convenience of a real PVR which is having all the controls at your fingertips. Namely a full-function remote control to pause, rewind , fast forward, slomo, access the channel guide, schedule recordings, etc...
You have to access the program's menus with a mouse, which is a real pain when you're trying to change channels or pause.
This is totally untrue. You can very easily get a remote control for your PC - in fact remote controls with IR receivers and IR blasters are often bundled with TV tuner cards, although not necessarily OTA tuner cards. There is even a specific remote control sold by MS for Windows Media Center. Windows Media Center, BeyondTV, SageTV and MythTV are all designed to be used by a remote control from a destance - the UI for WinMC is often called a 10 foot UI since it is meant to be used from 10 feet away sitting on your coach and uses large fonts that are readable from that distance.
You can also buy remote controls for PCs for <$20 on eBay. Once you have an IR receiver on your PC you can also use external programs like Girder or EventGhost although they are not necessary for most PVR functions. You also have the option of using a keyboard which is a better way to enter text when searching for TV shows.
I use the same Harmony remote with my HTPC that I use with my cable box, DVD player, AVR, etc.
There are inital setup issues with getting the TV guide data in Windows Media Center but that is a one-time issue and once you have that done you are set. There are also other PVR software options such as MythTV (for Linux) and SageTV (for Windows, Mac, Linux) that work perfectly with Canadian OTA.
HTPCs also offer a whole bunch of other functionality, such as ability to playback other media files (i.e. downloaded movies, music, etc), ability to watch online streaming video from TV network websites or Youtube, ability to transfer your shows to other PCs or burn to DVD/BluRay, ability to automagically skip commercials, ability to integrate several different sources (OTA+cable) in one system, ability to have several tuners to record several channels at once, ability to add more hard drive storage as required, etc.
They can be more expensive initially and more work to set up and maintain but they offer a premium solution to this issue. There is also no subscription fee required.