Yes..
Both products need to be Volume License products with Volume License keys to
be within licensing requirements.
Naturally you will need to install these products in "install mode" (change
user /install) on the term server.
First install Office 2003.
Then install office 2007. Use a .msp created with the OCT and specify to NOT
remove previous versions of office (except outlook). You cannot run both
versions of outlook on one machine.
Then change the mode back to execute mode. (Change user /execute)