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.