Performance Monitor is a small program that shows you the CPU, Memory, Disk and Network utilization under Windows NT platforms. It's composed by four fully configurable small graphs and it can work in the tray area also.
PerfMon can become transparent and permits you to forward left-mouse clicks so you can place it anywhere. You can also change the program priority (saving CPU work) and its size (for big monitor resolutions ;-))
Usage:
Right-click for options
Drag a single panel to move it
Drag a single panel with the CTRL Key down to move all attached panels
CrystalDiskInfo is an Open Source utility that monitors and displays the health of your hard drive, including basic information, S.M.A.R.T. values, and disk temperature. Also available as a portable version.
PRTG - Free Network Monitor is a network monitoring solution that ensures the availability of network components while also measuring traffic and usage.
CrystalDiskInfo Portable is an Open Source utility that monitors and displays the health of your hard drive, including basic information, S.M.A.R.T. values, and disk temperature. Also available as an installer.
Wireless Network Watcher is a small freeware monitoring tool that quickly scans your wireless network and then lists all the computers and devices that are currently connected.