You could get a TV tuner. You can get a PCI tuner, which in case you don't know, goes inside your computer in one of the expansion slots. You can also get an external TV Tuner which plugs in USB.
Yeah, PCI or even USB tuners are not that expensive. Some PCI TV Tuner cards sport RCA or S-video ports that allow you to connect up your DVD player or VCR up to your computer as well.