clean upgrade 32 -> 64?

[Joe Pfeiffer <pfeiffer@cs.nmsu.edu>]

I'm about to replace one of my old 32-bit x86 Debian boxes with a
64-bit; I'll actually just be moving the disk drives out of the old box
into the new one and doing any minor configuration changes that'll be
neede (which will be very minor).  So, while I'm at it, I'm curious --
is there any clean way to do an update that will simply replace all the
32 bit packages with 64 (and do all the other necessary multiarch
stuff)?

I'm not actually doing anything with it that will require 64 bits; if
the answer is "no" I'll simply continue to run it as a 32 bit machine.

So, is it possible?

Thanks,