If feasabile, I would store my bags at a locker at the train station and tour the medieval Grand Place in Brussels, and perhaps a small and cheap meal of Moules/Mussels at the many seafood restaurants on the nearby streets. That way, you can see the best things in Brussels! I think that this should take no more than a couple of hours.
[This message has been edited by DOC 2 BE (edited 01-23-2001).]