I use Ad-Aware and I recommend it for your typical Adware/Malware. I also use Pest Patrol and Spybot.
When you install Ad-aware make sure you select the option to download the updated definitions (it should do this automatically when you first install the program, but you'll need to do it each time you want to run a scan to ensure that you have the most updated version of it). When you choose Scan, you want to select a "Full System Scan" rather than a Smart Scan. This is more in-depth and occasionally finds more than the Smart Scan does.
Sometimes it's best to do this in Safe Mode to ensure proper removal of things, but let's start here.
Ryan