First of all I am not a DBA. I have a win 7 box and a co-worker has a 2008 Server box. We both have SQLEXPRESS installed. I enabled all the connections (i.e. TCP) and have added the user using windows authentication. I gave him dbo and restarted the SQL service. Can I do this? If so, what else do I need to do to allow others to connect to my SQL db's
You need to enable remote connections (right-click on server name in SSMS object explorer, then Server Properties -> Connections tab). If that does not fix the issue, make sure the service is running (look in services.msc), and that your colleague is using the correct server name (for sql express the format would be SERVERNAME\SQLEXPRESS).