Though I'm a Mac guy, my (limited) understanding of Windows security is that it has restrictions around running Javascript files "locally." Your best bet would be to copy the file to your web application's directory structure and reference it through a relative path.
Not only will this provide greater reliability, but it's also one less thing to remember to include when deploying to a web server or somesuch. If the JS file is outside your app's folder structure, when deploying to a remote server you'll have to include it anyways.