WinDVD that comes with it is pretty good but WinDVD 5 supposedly has some power management features. I don’t know how much it really can save you. The biggest power drain is the screen and the drive itself and not the program.
You’re better off lowering the brightness levels as your best bet for conserving battery life. You can’t really do a lot about the DVD drive unless you rip your DVD onto the hard disk and then disable the DVD drive.