>>Look at PCTV Deluxe. And try a "PCTV Deluxe" search on Google. Not cheap, but...
>
>I took a look at that but haven't seen anything that it supports simultaneous channels. I'll go back with ATI to see if they released a more fancy one since then.

PCTV is no different in functionality than ATI TV Tuner.
Some kind of software may combine 4 signals into the split window, but you have to have 4 different signal sources in the first place. One TV channel on screen means that TV Tuner is physically tuned to the corresponding frequency. To have 4 channels simultaneously, you have to physically tune 4 different devices (tuners) to different frequencies. Or scan 4 frequencies (channels) in a loop, which means splitting the frame rate between them. That's what ATI does in Channel preview mode by refreshing the picture for each channel window one after another.
So it is a hardware issue. :)