WHY? Because the page file is used for more than paging. It’s also used as a backing file for modified memory. In a nutshell (and I’m simplifying here), windows must be able to write any piece of memory to a file, and YOU CANT STOP IT. If you have a page of memory that was read in from an executable program and one of those pages has changed, Windows must have some place to write the changed copy of the file. If the page hasn’t changed, it can just read it from the disk again. If it has changed, Windows will at some point write that page to a disk file. Windows can do this at any time up until that program terminates.

When it writes any changed pages to a disk file, where does it write them? The page file. It’s not intuitive, but it’s what happens. It’s a little bit different than the way you normally think of memory being paged.

Even when you turn the page file off, this is still happening behing the scenes.

To accomplish what you are looking to do, look for the Microsoft dynamic cache update. It will help clear up the dysfuncitonal caching algorithms in 20003/vista/2008. Read the directions 10 times. There are some subtle things in there that if you don’t follow them exactly, the update does nothing for you. Best to just allocate the cache once across the board instead of on a per application basis.

Like you, it seems like there’s still a fair bit of memory available at the time in the system. I thought perhaps it was just my machine, but it’s got to be something about running Vista with virtual memory disabled.