If you know the name of the file go to Start>Search>All Files and Folders and type in the file name. Then when the search is complete Delete the file and any associations. Or download http://www.safer-networking.org/en/download/index.html
I've used these two for many years. I run them at least once a week. They have "free" versions that you will manually have to perform the "updates". The pay-for versions will also dynamically monitor for spyware plants. I run these two because one may not catch what the other will.
http://www.lavasoft.com/
http://www.spybot.com/en/index.html
I also have been using both of those programs for years now. The computer I use I built from scratch, So I know some things about IT.