The Radeons left this huge black border around my screen, and I couldn't get it to go away.
This is an overscan issue. If I understand this correctly, ATi defaults to some normalized value where nVidia defaults to full overscan. It could be ATi has a reason not to default to full overscan, but every HDTV I've hooked a computer up to needs the full overscan to fill the screen. You can adjust this in the scaling tab under display configuration in Catalyst. Under the desktop and displays category, click the little triangle on the display of interest and go to configure. A search on ATI overscan should resolve any ambiguities.
I've also gone through many cards, both ATi and nVidia. I've found my share of issues with both companies and find both companies products to be workable when you understand the issue to avoid. Ever since ATi started using the dotnet framework to write their driver UI, I've felt their drivers where bloated. That said, I felt nVidia's were bloated before that and they seem less bloated now by comparison. The biggest issue I've had with ATi's drivers is the UI layout. By comparison, nVidia's are easier to navigate, and adjust. Another short coming of ATi's drivers has been multiGPU setups. Recently, this shortcoming has been largely rectified. The final shortcoming of ATi drivers has to do with new game releases. Because of nVidia's developer relations, ATi is often forced to wait until after game release to resolve issues. Given that nVidia has access to developers to resolve issues well before the release of the game, the one to two months I've had to wait for ATi to catch up after game release doesn't seem all that unreasonable. However, I'm the kind of person who likes to wait and see how well a game reviews before I purchase it, so I usually don't even feel the wait.
The largest issues I've had with nVidia's drivers had to do with occasional stability issues, optimization tricks with noticeable quality degradation, and inferior filtering techniques. Stability issues are normally a single release issue, so I just revert to the previous driver until the next update. ATi is guilty of over optimizing as well, but to their credit, theirs has largely been less noticeable and more often than not a response to nVidia. To be specific, nVidia's filtering isn't bad, but rather, ATi seems to keep a step ahead of them.
I've preferred ATi for my HTPC cards since the Rage Pro days (think All-In-Wonder). I prefer nVidia for compute applications like Folding@home and some of the new Photoshop filters. My gaming PC goes back and forth depending on what makes the most sense. Notebooks are a mixed bag. nVidia had all those unreliable chips in their 8000 series and derivatives, but that is an issue largely past. ATi chips are more power efficient, but nVidia had the only graphics switching technology until very recently. I still don't have a feel for how well ATi's works. In any case, until ATi can at least match nVidia's optimus technology, I prefer nVidia for mainstream and lower chips. ATi chips make more sense at the high end owing in part to a lack of designs using optimus. The fact that the ATi chips are less power hungry and consequently cooler makes me a little more comfortable with their reliability (assuming the manufacturer doesn't cut corners on cooling).
Both companies have had their foul ups, some larger than others (FX series, HD2000 series). It's not something I hold against them. Their business practices and handling of major problems has longer lasting effects. Because of this, when I am presented with an overall equal product from both ATi and nVidia, I will go ATi. However, given that I consider price, performance, customer support, heat, noise, power consumption, ect., their is rarely a product I consider equal. As such I currently have two ATi cards, two nVidia cards, and one nVidia mobile solution. That said, it just so happens that I've put more ATi cards into systems I've built for others recently due to price/performance.