Ask the previous owner for the software that came with the tv tuner. Or
check with the support site for said tv tuner.

wrote:

I've seen the ads on tv that say you can record tv on your computer
with Vista. I have a laptop with vista, but I would need to buy a tv
tuner.

My desktop can with a tv tuner which I have never used. I'd like to
try it first since I already have the hardware, and the desktop stays
on most of the time anyway. But what software do I need to use? As far
as I can windows media center only works with vista, and I don't want
to upgrade my desktop to vista. I would also assume that the previous
owner, who installed the tv tuner, must have watched tv on this
computer.

What software should I be looking for?