SystemPanel is a cool app. It is mainly used to provide critical system info to you such as the main app users of CPU, how much memory you have left, and most importantly which applications are running (and in what capacity).
If you look at the top of your list it says Active Applications (those currently running). It further breaks them down into "foreground" and "background," meaning those apps that are running and consuming CPU and those that are running but in the "background," consuming very little CPU.
You can use this as a task killer but I don't believe you can set it to run at intervals. Simply hit "End All" and it will kill everything except for your excluded tasks. If you see a process that you'd like to see running no matter what (for example, I use Beautiful Widgets on my home screen so I don't want that to be killed), long-press it, click "details" and press "Exclude!". Now, on the main screen, there will be a little blue bar next to it. This means that if you hit the button "End All", this process won't be killed.
You can also place a widget to "End All" on your home screen. Personally I use this more for system information and less as a task killer, even though it can be used as such.
Hope this helps, it's a great app!!