Unable to make any .NET connection to MSSQL Server 2008 Express

Target: Microsoft SQL Server Express Edition with Advanced Services (64-bit)
OS: Microsoft Windows NT 6.1 (7601)
Version: 10.50.1600.1

I have tried close to 30 various of the following, none of which work, any insight/suggestions would be great appreciated!

user id=myUserID;password=WeNeed8cess;
server=DFSWORKBOX\SQLEXPRESS;
Initial Catalog=TestDB;
Trusted_Connection=yes;Integrated Security=SSPI;

Simply trying to implement SqlConnection myConnection = new SqlConnection(connectStr);
myConnection.Open()....which always fails!