A word of advise, NPE-300s are end of life and Cisco is going to do End of Support for these NPE's by Dec 2006. I would not invest money now to buy memory chips for a module (unless you rely on third party memory, which Cisco TAC does not support).
NPE-G1 is the replacement module for the NPE-300 and they come with 1 gig of memory.
Now to answer your question, I am not sure if you can see memory configs like you do in 3600s, using a command. Your 7200 NPE has 32 MB of fixed memory and on bank 1 and bank 2, it could be two 32's or one 64MB.
HTH
Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus