How do I map a network drive that requires a username and password in .NET?

Have you looked at this?

http://www.codeguru.com/csharp/csharp/cs_network/windowsservices/article.php/c12357

Also, you could just use net.exe via Process.Start() and pass it the parameters you've always used in the code below:

System.Diagnostics.Process.Start("net.exe", "use K: \\\\Server\\URI\\path\\here");

This can also be used without a drive letter and then accessed through the UNC path.

 System.Diagnostics.Process.Start("net.exe", @"use @"\\Server\URI\path\here");
 System.IO.File.Copy(@"\\Server\URI\path\here\somefile.abc", destFile, true);