I previously ran 10.3.9 before upgrading to 10.4. I also use PowerPoint almost every day. Under 10.3.9, I never had any memory problems with my iBook G4 512MB. PowerPoint typically used around 40MB of memory and I almost never had any VM page-outs. However, with 10.4, PowerPoint sometimes exploded into using over 300MB! My files weren't large, so I think this was clearly a 10.4 problem. I had hundreds of page-outs and my system ran really slow. However, with the 10.4.1 update, by memory usage is back to normal and I never have any page-outs. This was a nice update from Apple.
Edit: fixed page-ins to page-outs. I meant to say that the VM loads files back to ram.
Edit: fixed page-ins to page-outs. I meant to say that the VM loads files back to ram.