Strange! I live in this town for ages and I never saw this meseum before, and my sons who still ive…read morether had never heard of it. It is a small one - once more ina beautiful old house in the Katelijne Street - the one you need to take to go and visit the "Groot Begijnhof". It concentrates on the work of the "mad" Flemish painters from the 16th century and their offspring (Breughel, Brouwers, Bosch and some others) and has some nice originals that were unknown to me (next to some copies, but OK, this is a small and cheap museum!)
All in all, you can do the round of the museum in about half an hour for 3EUR: a very good offer indeed..