System Activity Logger



I've found on the net several freeware/shareware programs which can track down all system activity (including network).

I wonder if there is someting similar in Windows XP; a service and a UI like Event Viewer, to log all system activity, even when the computer is idle.

If there is such service, how can I configure it, or start it ? It could create a log file somewhere? Is that information encrypted or password protected?
.