i've got a PCI one in my desktop...though you wouldn't be able to use one like that so it really doesn't help you much.
but i really like mine though, they're pretty useful but since TV's use something like 640x480 resolution it gets a little annoying on the computer monitor as i'm used to a 1440x900 monitor.
so yeah, i'd definately say that's the only real setback for them...that the highest resolution you can get them to work at is 640x480 but you can still do fullscreen and stuff and it'll be very watchable unless you're obsesive compulsive about that kinda thing.
Antec NeoPower 650W
Intel Core 2 Duo E8400 (w/ Arctic Freezer 7)
4GB DDR2-1000 G.Skill
Sapphire x1950 Pro 512mb (w/ V700)
250GB, 500GB and 1.5TB Seagate Barracudas (2.25TB total)
Fatal1ty XtremeGamer sound card *** generic TV tuner
Xclio 3060 case *** HannsG 22" monitor
XP Pro / Ubuntu 7.10 *** Razer Copperhead and Tarantula