Well, its nothing special for the ati card, it uses a std antenna.
You could put rabit ears on it, I modified an amplified antenna for my setup, and ran the telescoping metal along the edges of the back windshield.
Some other options,
The systems you hear people talking about are "Diversity Antena systems" I have seen one by magnavog and pionear, they have 4 elements to pick up a signal, the brain of the system has a chip inside that looks at each element , and picks the best 2 for use, and continues to sample and switch the signal as you move around. they tend to be really expensive though. And IMHO - useless.
Honestly - I have an ATI AIW pro.
I do like it, I use the dvd, and sometimes the tv, but I really think if I did it over, I would use an external (USB or maybe just a plain old tuner) tv tuner. I only get 1 - 4 chanels most of the time, and reception is poor, I think It has to do with noise from the PSU, or something. but I know if I take a pocket sized tv and mount it on the dash, I get beter reception.
Just my .02