32 to 64 bit change over

Greetings, one and all,

I have some very large memory bound queries being run in postgres.
The documentation seems to say that I would be able to get more use
out of the available memory if I were running the 64 bit postgres
instead of the current 32 bit.  We have the binaries for both.  What
would be the ramifications to changing from the 32 bit to the 64 bit
process?

Thanks,
Carol