excessive paging with free ram (a mysterious 600MB limit?)

Hi all,

I am getting this behavior on two different MBP (10.4.9).

They both have 2GB of RAM.

I seem unable to get below than 600MB free. As I approach
that threshold, pageouts go up.

If I am near that 600MB threshold, I can open another app and
voila — more pageouts.

This last 600MB RAM never seems to get used (about 85% of it is
“inactive”, but that shouldn’t matter, right?).

Does the kernel have a threshold set too high for paging? Is there a variable
somewhere I can adjust? Will it only allow a certain amount of RAM per user
(I am running these machines with typically only one user)?

Any help would be greatly appreciated.

Thanks,
Jason