I would actually recommend that you look closely at moving your whole design to the 3.3 volt realm. It is the way of the world today. It is fun running the scope at 1 v/cm instead of 2 v/cm.

Michael Karas

PS. Note that the full Cygnal line is all 3.3 volt stuff with 5 volt tolarant I/O and so if you still have some 5v I/O left oh well it can be accomodated.

PPS. Overall it is my feeling that filling a board up with extra components just so you can keep old architecture stuff is kind of silly. Look closely at how you can build your stuff with one power supply and even though some components may end up with a higher per component cost you may very well realize a lower overall system cost. This can be due to smaller circuit boards, higher integration of other logic with the processor, and smaller surface mount package sizes.
MJK