Hi mixture. What shows up as Memoria Física (it's in Spanish but corresponds to the Page File Usage History graph on My XP) is sitting pretty steady at 44 to 46% when pretty well nothing is going on. At the same time the processor usage is rapidly and constantly jumping all over the place from 2% to 70% with bursts to 100% fairly often.
When I've see the hard drive occupation it's via the pie chart on the main page of Defraggler and when I have that running I have everything manually controllable turned off always, so that much is a constant and the computer should always be doing as near to nothing as the OS and the startup menu allow. Right now I booted it to get then figures to answer your question and closed down even the two very small things which she-who-must-be-obeyed won't let me disable on the startup menu, yet still the CPU use is jumping all over the place as I described above.