Have you tried "sharing" the files on the desktop PC?
I'm not sure that you can legitimately share the "desktop". You might have to move the files into the "Shared Documents" and then maybe into the "Shared Music" folder.
Try moving one of the files in there and then, on the laptop, click on the Start button, then "My Network Places" and see if you can see the other PC. It helps if you've given the other PC a name that is obvious (some people theme their PC names on a network, e.g. Kirk, Spock, Janeway, etc.).
If you can see it, look for the connection that has "Shared Docs" in it, and double click on that. You should then be able to see the file that you put there.
Let me know how you get on.
ST