There was an old post here describing some T-SQL code for finding the number of weekdays between two dates, which I wrote. It was working fine, so if you have implemented it you have not done anything wrong. However, Jeff Moden from SQL Server Central has written a post a while ago about this same problem and his implementation is a bit cleaner, and thus I would consider it better than mine. So, here is the link:
http://www.sqlservercentral.com/articles/Advanced+Querying/calculatingworkdays/1660/
Boyan Penev on Microsoft BI 