Here's what I recommend:

1. Let's play either Chapter 1 of the campaign, or try the Diablo conversion. It looks fun!
2. Go to this page to set up the Diablo conversion: click here. You need to download three files (plus the optional music file); two of the files are over 100 meg, so put some time aside for it before the game.
3. I'm trying to get a server set up on Johnny's machine. I'll blog shortly with details.