When I had my 6700, I had discovered that the OS (and I am sure on the Mogul too) was only using some, not all of the power states. I will have to play around with it, but I used one state to leave the display on, without backlight before it went into sleep mode. I also setup the wav device to be on in sleep mode to improve the ring speed.
Will have to poke around to see if you can just dim the screen...
The state that I was playing with was called UserIdle and can be found in HKEY_LOCAL_MACHINE\System\CurrentControlSet\Contro l\Power\Timeouts
MSDN has good documentation on the power states...