The question you should be asking yourself is, why was my computer able to be exploited in the first place?
Switching to a different AV product won't make any difference if you fail to address the basic issues such as software patching.
You say that as though a fully patched system is immune to malware. The box was fully patched, as they always are in our house. I run secunia, Firefox plugin checker and Windows update regularly. It was infected by a drive-by on a legit site because, even when updated, Windows is a closed source system that has many holes. Even when made known vulnerabilities take up to a month to be patched and sometimes much longer. It doesn't help that even when malware is a year old, MS still haven't added signatures to MSE for it.

That's the reason only one box in our house runs Windows (and only then for Publisher), and is basically a throw-away install with an image ready to re-deploy in case of issues. Everything else runs Linux or OS X. Ironically I was running MSE at the recommendation of this forum, but since then (and with much testing of malware against suites in a VM), I run Webroot or Comodo with its integrated sandbox.
