Why not? Services.
When Windows services are idle, they are swapped out, to lessen consumption of system RAM. So, even if you had 2Gb of RAM, with 1.75Gb free, Windows would still want to assign a 32K system service to swap file after it had been idle for a certain period.
Have you ever noticed that when you wake your PC up after a period of inactivity, it thrashes the hard drives for a moment? That is Windows taking the now required services from the swapfile, and placing them back into real RAM.
My rule is, and I apply it to all my clients machines, heaps of RAM first, then a pagefile that starts at 2.5 times real RAM, and has no upper limit.
Used with Norton SpeedDisk, this allows you to have a perfectly contigous pagefile that rarely if evergrows.
Which is where I disagree with the "let Windows handle the pagefile" malarky. Great if you want a pagefile that ends up in a million pieces scattered around the hard drive. Definite performance issues will arise.
