Hi Cort,
It depends a bit on the features you need. If all you need to do is rotate ads, the built-in one is fine. At the other side of the spectrum you find commercial products such as this one from Telerik:
http://www.telerik.com/products/aspn...x/rotator.aspx
You could also build your own.
What the right choice is for you depends on your budget, time, and requirements.
Cheers,
Imar