More fiddling with the old Olympus camera revealed I had NOT set it up properly to create enlarged images. On the regular SHQ mode I can get up to 185 x 4MP shots on a 512 MB XD card. Now I have successfully dialled in the SHQ Enlarged mode, this maximum drops to 91 x 7MP shots.
Really neat how the elderly 4MP camera can spit out 7MP images.