PS C:\Documents and Settings\Administrator> set-executionpolicy Unrestricted
PS C:\Documents and Settings\Administrator>
Once you type that and press return key, you will be able to execute your .ps1 script file without any problems. Regarding execution policy options, it is likely candidate for a separate blog post!
You can have a more detailed look regarding execution policy options here http://www.informit.com/articles/article.aspx?p=729101&seqNum=7