I think you will find it hard to get card specific drivers for tv tuner cards. Plus you also need tuning software which is not in leopard. Many USB tuners will work with elgato eyetv, if you are lucky yours might work. I bought a elgato USB tuner and it works very well, but for the best tv experience you should use vista media center to watch and record tv, with a bit of effort I got the epg in media center that will do simple recording and also automatically record shows whenever they are on. The epg in media center kicks ass on the eyetv epg. To make up your own mind you would have to try both.
Eyetv has some cool features though I would recommend getting the full remote as I only have the mac remote and it sucks compared to the media center remote.

Good luck, sorry to say I don't think you will find and drivers for pci tuner cards as companys that make them just don't support mac as tuning software is needed too.