Perfmon is a tool that allows user-level code to access the performance counters present in XP. It allows you to open a Windows XP Performance console configured with settings files.

This performance data encompasses an enormously rich set of metrics on resource usage of key hardware and software components that is available on every Windows XP/2000 and 2003 server.

Go to Start -> Run and type perfmon (see picture 1).

Picture 1

It looks a bit daunting the first time you see it (see picture 2), but it doesn't take long to get used to reading it, it covers all the performance monitors like Drive speed, disk access, network stats etc.

Picture 2