simple-GT-monitor is a Superkaramba theme that will provide all the information you want about your system.
To use it, uncompress it and load simple-GT-monitor.theme with superkaramba. You may want to open .theme file with your favorite editor and change the mount points, the disks or the network interface (eth0, wlan0, ...) according to your needs.
The CPU info field is clickable and provides some additional infos about your CPU.
Background is from system2free theme, modified by me for my 1280x1024 screen resolution.