HijackThis

This program is not really a standalone spyware remover. However, if you know what you're doing, it can be a great way to locate programs that may be silently playing havoc with your computer. What it does is examine critical parts of the operating system, such as the registry and browser, and produce a list of all programs affecting those areas. This list can give a knowledgeable user an idea of what programs might be doing something they shouldn't. While HijackThis does give you the option to "Fix", or remove, an entry, it is a bad idea to actually do this unless you're absolutely sure the entry is malicious. Instead, you can look up the program on a spyware site and see if it's actually spyware, or ask an expert for help.

This program also offers some very powerful tools for experts, including a process manager and a hosts file editor, although you shouldn't mess with these unless you know how to use them. While HijackThis isn't for everyone, it can be the perfect way to get rid of a spyware infection that regular programs can't.