If you aren't comfortable doing reg edits and want tweaks to increase battery life and get rid of the message sent popup (and many other mods), install some cabs found here -
http://forum.ppcgeeks.com/showthread.php?t=10668
And the nice thing is, you can easily uninstall them if needed. codyppc has done some nice work. I installed the battery hack only cab found in the second post and the no message sent cab in the first, among others. Hope it helps.