Mike,
The vast majority of us that use laptops use them as storage devices for midi files, lyrics and MP3s. While there is software that you can also use, Band In A Box, etc, it is slow and combersome for the performing musician/OMB. By using programs such as VanBasco's Midi/Karaoke Player and firing it from the laptop through the keyboard, you get incredible midi sounds that cannot be beat.
Essentially, the laptop is just another great tool that helps eliminate dead time between songs, plus you can instantly display the lyrics of any song with the appropriate keyboard settings--kinda' takes the guesswork out of things.
Gary
_________________________
PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)