Any of you use Office. If so the pop up ballons telling you what the buttons do is a typical Microsoft feature. Ok, with that said if you can't find a prefference option to kill it, you get to live with it.
If i'm not mistaken, the balloon should only pop up if the cursor sits on a button for an extended period of time. So, if you put the curisor just outside of the applications window the balloons should not appear. Also, I will confirm that the balloons are not controled by Apple's Balloon help. That would be too logical for Microsoft.
Sometimes I love Microsoft for Office and Explorer, other times I hate them for their hacked up ports of apps that they can't not make for the Mac community. Go figure!