TV tuner cards in the $30-45 range shuld work (See Newegg "Video Device & Add On " section). One popular brand is Leadtek but if you want to get a cheap one the $30 KWorld seems to work once you get it set up:
" ***** Sputnik,11/22/2004 10:11:03 AM
I bought 1 of these, demo'd it out and bought 2 more for the rest of my kids' PCs. The goal here was to eliminate the seperate need for a TV in each of the kids' rooms, and it definitely accomplishes that goal. The software is kind of nasty to get set up correctly with XP. Had to install from the disk, and then install the latest driver and software from their site over the top of the oem software to finally get it working. The hardware driver from Windows update breaks it as well.. However, once it is working.. it works great for the budget price. Can't go wrong. The best parts are the remote shutdown of the PC, the timer that automatically shuts down the PC after a specified interval.. good stuff. The FM tuner is a little clunky to run until you get the presets programmed in, then it is fine. I had to manually change all the stations in TV mode to stereo broadcast as well, it defaulted all of them to mono. Doesn't seem to require any maintenance once working.. 7 yr old and 5yr old friendly.
The TV and radio recording functions seem to work good as well. The thing says it can record TV without the computer being on initially as well.. haven't messed with that. "