Well, I think I have to sheepishly withdraw my question.
A little bit before I installed my hipix, I setup netmeeting to do desktop sharing. I read someplace after install of hipix that ATI AIW radeon had a conflict with Hipix, so I accepted the loss of my ntsc video capture for the time being.
As a result of people posting that it worked fine for them I dug around ATIs site, which suggests to solutions to the problem I was haivng: 1) quit background apps, especially video confereng or video capture 2) install directx 8.0a digital video update
I had already installed the digital video update, but I tried re installing it, but it asked me if I wanted to reboot and I was downloading something else. Then it occurred to me to try and turn off netmeeting desktop sharing. which I did. I was then able to use the ATI multimedia center and get TV input.
So thank you to those of you who corrected my mistaken belief that there was a conflict.
And for all you people having a problem with ATI AIW, check and make sure netmeeting or other conferencing software isn't the source of the conflict.
Sorry hipix for blaming you!