Freeware: Perfmon

Performance Monitor 3.8.5Performance Monitor is a program that shows you the CPU, Memory, Disk and Network utilization under Windows NT platforms (2000, XP+). It's composed by four fully configurable small graphs and it can work in the tray area also.

CPUMonCPUMon is an advanced performance measurement tool. Its combination GUI/device driver make the wide range of processor performance counters present on the Pentium, Pentium Pro and Pentium II/III, easily accessible.

Net-Probe 3.0.0Networked device monitoring, integrating graphs, alarms, GPS tracking and actions (send email, SMS, service restart etc) onto a rich graphical representation. Wizard Based, including setup wizard used to scan&draw a network in a few steps.