Pesonally, I wouldn't use a SDIO TV card much. Broadcast channels just really aren't what they used to be BC (before cable), so other than PBS, NBC, CBS, ABC, and the local FOX affilate, I doubt I could get much.
In the meantime, I use my PC (which has two TV cards for a total of three TV tuners) to record all my TV shows just like a Tivo device. The software I use is GBPVR (freeware). It records in MPEG2 format, but you can configure it to do a post processing transcode to DivX, too. Copy the files to an SD card, play it in your Palm with TCPMP. You can even configure GBPVR to automatically skip/edit out commercials. All the benefits of Tivo (for free) with the added benefit of a portable device.