c# 2008 SQL Server Express Connection String

Remove Integrated Security=True from your connection string and (optional) add Persist Security Info=True;

From MSDN:

Integrated Security - When false, User ID and Password are specified in the connection. When true, the current Windows account credentials are used for authentication.

try this

string sqlcon=("Data Source="your pc name\\SQLEXPRESS"; 
UserID=sa;
Password=****;
Initial Catalog="+MyDatabase+"; 
IntegratedSecurity=True;");