The 6800 gt should not have been an improvement in performacne for you lee.
I went from a 6800ultra OC to my current card and in generally everything I use the product for, it is faster than my last card, cept in d3 which I never play anyways.
Functionality is better too but everyone has their own personal needs and requirements.
The 7800gt would be a decent option for an upgrade I guess but no tv tuner. I know you have had issues but not all the issues are resident to the AIW card. The worst drivers on the market are made by creative. I had so many issues I have been running a creative free setup for almost a year and a half now.
Doing research first and foremost is helpful.
Idle, in the $200-ish price-range, score a 7800gs if you can. By the middle of this year I will be moving probably to pci-e completely, depending on the quality and availability of the refresh AIW card from ATi, will see how compliant it is with HDCP standards
and also what kind of budget I have remaining for the 2707 Ultrasharp from Dell at the time lol.