I have a similar problem with my Pinnacle 310i tuner card - no Pinnacle software for X64. Pinnacle say their engineers are working on it, but won't give any timing.
I'm assuming you have suitable drivers, and the system recognises your hardware. If so, have you tried Windows Media Centre? That works for me, though I have to admit, the picture quality isn't as good as it was when I ran the genuine Pinnacle Media Centre software previously on Win XP. I think that's a separate problem however.