Vista - New TV tuner card for slow computer, perhaps?

I have a Dell C521 with Vista Ultimate 64-bit, AMD 64x2 dual core 3800+/2.00 GHz, and GeForce 6150 LE with ATI Theater 650 Pro tuner, 9.1 driver.

I also have choppy TV live reception, some channels black with that combination. I understand, that this is probably due to a slow processor.

Somebody on this forum had similar problems and solved them by updating/tweaking his/her Hauppauge WinTV-HRV tuner drivers. The ATI theater doesn't have that option.

I am thinking of buying the Hauppauge WinTV-HVR-2250 card. I requires minimum 2.2 GHz, .2 more gigs than I have. Will it work anyway, if I declare myself satified with digital reception quality over the air only, and not the more GPU resource demanding HDTV. The Hauppauge card software has som interesting tweak options, see attachment. Hope very much somebody can help me with this!

Thanks - Ravn