Ad-Aware and SpyBot S&D are not mutually exclusive. ALthough they kinda do the same thing they do it differently and are maintained by different folks, so are inherently different. You can and should use both, they will each catch things that the other misses. If your browser was hijacked you might want to take a look at HiJackthis, available @ http://mjc1.com/mirror/hjt/
Make sure you also find a comprehensive HiJackThis log tutorial to take a look at the logs it produces. It is not as refined as Ad-Aware or SpyBot S&D, but is a nice addition to catch additional problems that they don't.

In addition to keep away from pop-ups either install the google tool bar to your IE, or switch to a different browser like Mozilla, Mozilla firebird, or Opera. I've tried all of these and they each have their good points.

Good Luck.