Perfgraph is a CPU / memory / network / hardware monitor. It is implemented as an Explorer toolbar so it does not necessarily take up space from your desktop.
A quick overview of its features:
CPU utilization display for up to 8 cores Memory utilization indicator Network throughput monitoring via SNMP Network performance & reliability monitoring by pinging remote hosts Hardware monitoring CPU temperatures Chipset temperatures & fan speeds HDD temperature Gigabyte Odin PSU support (voltage, current, power, etc.) Very lightweight: minimal CPU and memory utilization Perfgraph will run on both x86 and x64 versions of Windows XP or later.
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.