Since I don't have an ATI to give you the rundown on how to look, all I can say is you would check by going to ATI's website and downloading the newest set and installing them just to make sure...
But you skipped over an important question when you were answering. Do the spots appear all of the time or just in very specific situations? If it happens all of the time, there could be issues with your monitor or even something as simple as a loose or bad cable. In specific situations it could just be that your card doesn't like what's going on or even your directx is a little bad in which case, software updates are in order.
Also set your PC to the native resolution of the monitor. Don't be pretty sure, be absolutely sure. Looking crisp doesn't mean you're running at what you should be running at. Same thing for in game settings, match them to your screen's native resolution and settings.
Lastly about the lag... Again, is it all of the time, or just in certain situations? With Sins, especially late game, it's not necessarily how fast you can crunch numbers but how fast can you get data in and out of your RAM. If you've got crappy RAM, you're gonna lag late game.*
*According to Harpo's research and testing.