Malwarebytes its one of my favorite 'quick and easy' Antimalware programs to recommend. Download the free version, let it update, then run a quick scan and it takes care of 90% of the Malware programs my customers run into.
Microsoft Security Essentials
For most of my customers Microsoft Security Essentials is my prefered anti-malware solution these days. I usually recommend weekly scans with Malwarebytes as well. For my customers who do a lot of File Sharing and other activities which are more apt to get viruses I may recommend a more aggressive solution.
While the name sounds suspicious, SuperAntiSpyware is actually a very good on demand scanner. They have a portable version which clones its filename that allows you to remove those really tough malware that prevent you from installing/opening other anti-malware programs.