File access across the network, credentials, logonuser, impersonation

Hello,

I have an application that has both a server and client... the client can exist on any computer.

I have a need to allow a client to export a set of files. The server process that will be exporting the job runs as the Local System account.

When I want to export resources to a remote UNC such as \\servername\share that I don't have permission on I would like to prompt my user for credentials.

How do I then use these new credentials to authenticate and then System.IO.File.Copy(src,dst)

I've found several articles on impersonation and I can impersonate a local user, but not a remote user it seems...

I'm programming in C#.

Thanks,
Mike