After trying multiple times to get Microsoft Security Essentials to be less of a resource hog on Windows 7, I uninstalled that and went back to AVG on all of our home computers. In over 5 years, the only "infection" we've had to deal with was one or two cases of "scareware" that (in my experience, also including 1000+ computers supported at work) no anti-malware tool is capable of preventing (and luckily, are very easy to remove).
Malwarebytes is defnitely an excellent tool. Some of my co-workers believe the free edition can't be used except for personal (home) use, but I've scoured the web site (http://www.malwarebytes.org/) and didn't find any information to support that.
I would say that Combofix should only be used as a last-resort, when everything else fails and for some reason you don't want to start with a new load/image.
Some co-workers report good results with Norton Power Eraser (NPE), but I've found better results using Symantec Endpoint Protection, which we have licensing for on all of our work computers.
Though technically not a utility/program, another indispensible resource is the Bleeping Computer web site: http://www.bleepingcomputer.com. They have very detailed instructions for removing most malware (both manual and automated methods). In most cases I've seen, the automated recommendations usually involve RKill and Malwarebytes.
One last opinion: Secunia PSI is excellent for keeping your computers up-to-date on Windows patches & lets you know if an installed app needs to be updated.
Keep Up with TechRepublic