I haven't attempted using this yet, but I have a Avermedia (avertv.com) USB tuner (the name is the Hybrid Volar USB Stick, something like that). Anyway, the website does have beta drivers for linux. I previously used this tuner with an Aspire one (took all the system resources, but did work, with high def - occasional choppiness but definitely watchable).
The problem of course is, after the drivers I need a program that will allow for viewing, changing channels, something basic will do. Is there a linux program that will allow me to do that which is available? I haven't found anything concrete yet, I was thinking whatever dell releases for a program with the TV tuner they are bringing out may work, but in the meantime something else to try would be nice!