Ok, this one depends on type of television signal that you receive. Analog antenna, DVB-T, HDTV - it defines which TV capture card you will choose. As general advice, pick TWO same cards (or even better - one card with two tuners) because that is the only way to record one program while watching another (which is the comfort I've been accustomed to with my old VCR). Also, strongly prefer cards that have hardware MPEG encoder because that means less work for your CPU (less work == less power == less heat == less noise).
Since I have only analog cable signal in my apartment, my choice was Hauppauge WinTV-PVR-500 MCE that provides two analog TV tuners for my HTPC. Analog signals are hopefully abandoned in your neighborhood, so you'll probably want at least some DVB-T receiver card or even better full HDTV.
Many high class TV tuner cards also support plugging external video sources besides TV what makes them usable as decent video capture devices. Almost all of them support analog S-Video In and Composite In, but these are analog signals and mostly abandoned these days. Better solution would be if you could find tuner (capture) cards with HDMI (consumer electronics), DV (video cameras) or even DVB-S receivers (digital satellite). Anyhow, think twice about all video sources that you plan to use with your Home Theater PC and equip it with needed video capture cards. If it takes, buy several video capture cards, because the last thing you want is to have to buy another set-top-box every time new video source emerges.
