Hi
Try SuperAntiSpyware...
http://superantispyware.com/
Make a note of what it finds before you remove them, so we know what you are dealing with.
Check out the Microsoft Malware Removal Tool..
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and the Security Scanner...
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This is why it's a really good idea to have a disk image of your hard drive, when something like this happens you can just wipe the drive and restore it to a previous state where everything was working perfectly.
If it's "Torjon.Zbot" there are some removal software apps out there.
Be careful about who you get the fixes from, the guy who want to charge you $50 to fix it may be the guy put it on there to start with. That's why I'm starting with stuff from Microsoft...