If you meet the desktop software requirements and don't use animation in your slides, the Presenter-to-Go module from Margi Systems is a great way to ditch the laptop when you go make that next presentation.  I would sooner trust the Visor for showing a presentation than a Windows computer, and as easy as the PtG is to use, why not?  Handspring even used the Presenter-to-Go when introducing the Visor Edge at a press conference.

Update: Margi Systems has now released a Windows 2000 conduit for the PtG module.