I don't think there is a real disatvantage. Some may use Firewire some may use USB 2.0. Advantage is if you have USB you can sue them on both computers. You can get an OEM Kit of Windows XP Media Center Edition 2005, I use that to watch videos, photos listen to mp3 off my computer via my XBox (Extender) on my home stereo on big screen downstairs.
If you go to places like CompUSA they got plenty in stock. What I would do is buy a WinTV or so, if you don't like it 100%, return it and try another one. From older models there was a WinTV 5600 and 5200 (I think) and the 5200 actually worked much better on my particular PC. Now that could change between PC's so just try some out.