To remove the auto-startup you can delete the PeacePulse file from your Startup folder.
An easy way to find your Startup folder is:
Right click on the Windows Start menu and choose 'Explore'
Click the plus or arrow by 'All Users'
Click on the plus or arrow by 'Start Menu'
Click on the plus or arrow by 'Programs'
Click on 'Startup' folder
Click on the PeacePulse icon and press the delete key
and now PeacePulse will not launch your default browser when you start your PC.
PeacePulse installs a shortcut to your Windows Desktop so that you can start PeacePulse from there, or if you wish you can make PeacePulse.org your browsers home page so that when you start your browser PeacePulse will start. For more information please see the setup page http://www.gaiasoft.com/PeacePulse.nsf/2peacepulsesetup