The last driver to support the 7200 is Catalyst 6.11 (well, for XP anyway). If you're running XP you can get it here:
http://ati.amd.com/support/drivers/x...rer300-xp.html
I've no idea how well that driver works with the aquarium though. Get older drivers here:
http://ati.amd.com/support/drivers/x...evious-xp.html
(Including 6.5, which I'm using - well, I actually designed the ATi card I'm using and got a somewhat different driver from a bit of the ATi website you can't get at, but it's basically the same.)
John