TaskMeter lets you put your CPU usage graph right on your taskbar. You can also measure a wide variety of other things, including disk access, network access, context switches, memory usage, and many more. Anything you can monitor in performance monitor (perfmon), you can monitor in TaskMeter. You can even monitor statistics for different machines on your network!
Dock TaskMeter to any edge of any monitor, or put it inside your taskbar. It behaves exactly like any other "desk band" (aka explorer toolbar or taskbar toolbar) on the system.
TaskMeter supports multiple graphs, with multiple lines, and user-definable colors and font settings. XML data files make it easy to automate, and low resource consumption ensures you'll get accurate data.