connecting to a cifs or windows share on a nas device using a specificusername and password

In ASP.Net, how can we connect to a nas that uses cifs for its file
sharing protocol. Currently we should be able to provide the ip address
or hostname of the nas, the sharename along with any directories to go
directly into that sharename, and the username and password. This
username and password will not be on the server hosting the asp.net
pages from the local usernames and password.

Currently we can only try to impersonate a local username and password
that is already on the local server. What we want to do is normally
when trying to connect to a windows share, it tries your normal username
and password, and if that doesn't work, it asks for a username and
password. Rather we want to be able to access it by telling it what
username and password to use like you can with mounting a drive letter.

The server is windows 2003. The nas might also be part of a domain, but
if it's not and we can only put in just the username instead of the
domainname/username, that's fine too.

It is the dotnet 2.0 framework we are using here. We'd rather not use
3.0 right now.