Although Windows security has improved a lot recently malicious software haven't been sitting still. So, here's 5 tools I like to use when purging malware from any Windows system.
Microsoft Malicious Software Removal Tool - Despite all the bad rep Microsoft gets, they've actually made a simple to use yet effective tool for removing malware. This is a surgical tool though so it'll only remove a very small sub-set of all malware that's out there. A newer version is released every month so download the latest release every month for best effectiveness.
You can download it here.
Junk Removal Tool - Like Microsoft's tool this is a surgical tool. This one's designed for removing PUP (Potentially Unwanted Programs), typically toolbars that get installed alongside various free software.
Here's the place to download JRT.
Malwarebytes Anti-malware - This is a must-have malware removal tool. Lots of stuff missed out by antivirus software get picked off by this guy.
Download the free version here.
Spybot Search & Destroy - Another must-have that also picks off stuff others miss. Unfortunately, I don't quite like the newer version 2 UI. I stick to the older 1.6.2 release but the newer versions should be just as good, if a little confusing to use. Get it here.
Eset Online Scanner - This is an online antivirus scanner so you'll need the Internet to run it. I find Eset's engine tends to find stuff where other antivirus software finds nothing. Use it here, or download the app if you don't use Internet Explorer.
No single tool can detect/remove every single malware out there so it's prudent to make use of as many varieties of tools as possible to clean up a system that's been compromised.