Okay so i took screenshot while in GuildWars in approx same location:
HighQuality setting:

HighPerformance setting:

I can't really tell any difference maybe with one of the two newer drivers you can but just wanted to show screenshot of approx. same spot one with HighPerformace and one with HighQuality set.
HighQuality setting:

HighPerformance setting:

I can't really tell any difference maybe with one of the two newer drivers you can but just wanted to show screenshot of approx. same spot one with HighPerformace and one with HighQuality set.






Fraps and download the free version. Displays FPS, Timed Screenshots (ie every 5, 10,22 seconds), 60 Second Movie Capture, Overlay Options, Detailed Benchmark Statistic and more... err maybe that covers it. 