As for this software, much of this functionality is built-in to Battery Management tools which also have the additional benefit of helping you to conserve power. I've been using one such tool myself for two months now and have quickly become a fan. Maybe I'll write a review for it soon - for both our sites...

However, when carrying out computer intensive activities, i.e. video rendering, disk imaging – anytime I don't want the computer to shutdown,  I use High Performance.

Up to recently, to change the power plan required me to open the Control Panel, then Power Options, and then select the required plan.  Now I have found a free gadget which the Developer claims:

       – Shows the active power plan with an icon and a tool tip in the system try

       – Right click the icon to get the list of available plans and change it 

       – Lists all plans even the user defined ones

       – Always updates status even when the plan is changed externally

       – The list is always updated with latest additions/removals

       – Automatic management of power scheme depending on the power line AC/battery

       – Set a plan when Battery Life % is less than a value

The application is only for Win 7 and is in beta, but I have used it fairly intensively for the last 5 weeks with absolutely no problems.

I can only strongly recommend it.  It can be found at:

http://powerschemeswitcher.codeplex.com/

Note: It needs no registration and there is no hint of a donation request.  The guy has produced a neat little program and deserves support.  Go have look!