Anyone know which edition of Netter's we need?

I'm a little lost as to the edition we're going to need--

From the book list posted in May:

Atlas of Human Anatomy, Frank Netter, 3rd edition, 2002, Icon Learning Systems.
....which I guess corresponds to ISBN 1929007116 (Amazon's page link)

but there's also a brand new 4th edition out as of June 2006: ISBN 1416033858--seemingly newfangled with some kind of online access.

Help?

Thanks!
~Leigh