UPS and PowerChute Software-necessary?

I have a APC Back-Ups 650 that connects to my comp with a serial cable. I noticed in control panel, in power options, XP has an option to shut down the computer if power is off more a certain time. Does this option really work?
It also asks to specify a program to run if power goes out for a certain amount of time... What type of program should be run?

Is it really necessary for me to install the power chute software since XP can manage the UPS? I know the UPS works fine when the power goes off, but don't know if the computer shuts off..

thanks for reading.

 

do a board search
this has been covered before
basic answer
Powershute has much more then xp, use Powershute