I would recommend that you download a program called Malwarebytes (malwarebytes.org) Just get the freeware version. It has been the best malware removal program we have found (I actually do computers for a living LOL). It is not an antivirus that runs all the time, but when you run it, it will remove the spyware and other malware that can really slowdown your computer. We run it about every 3 months on all of our computers.

AVG is a pretty good virus scan software. We have a non-profit company that we maintain computers for and they run it on all their computers. They haven't had any issues in the 5 years we have supported them.