Windows XP and Vista have a feature called Offline Files (previously known as
Offline Folders) that allows you to mark particular folders (and their sub-folders)
to be available offline. When you are on the network, Offline Files automatically
synchronizes the folders so that you have a copy of them locally on your hard
disk. Then when you are offline (and don't have access to the actual server),
Offline Files makes it look like you are online by simply accessing the locally
cached copy. Later, when you do have access to the file share, Offline Files
automatically synchronizes any changes you have made offline with the online
version and vice-versa.
To use Offline Files in MediaMonkey, just make sure to scan the network location
using a full UNC path. e.g. instead of scanning a mapped network drive such as
N:NASMusic, scan \\SERVERNAME\NAS\Music. If you prefer not to use the Offline
Files feature, you can also take advantage of MediaMonkey's built-in Virtual CD
function to cache external CDs or Network Content.