Use these along with an antivirus program, which is essential for a Windows computer.
SUPERAntiSpyware: Gets rid of cookies and other more obvious threats.
Malwarebytes Anti-Malware: Pretty self-explanatory — this utility scrubs malware.
Combofix: I’m not sure about this one. McAfee antivirus detected several supposed trojans when I tried to run Combofix, which could have been a fluke, but it could also indicate the version of Combofix I downloaded isn’t safe.
TDSSKiller.exe: This utility from Kaspersky is supposed to get at some of the more difficult trojans that can infect your computer.