Answering a forum post today, I just realized a feature that I never tried to use on Vista, Windows SideShow.
Info: Windows SideShow will also available on Windows 7.
And the good news is that we can use Windows Mobile (5 and 6) as SideShow device and use it to control our PowerPoint presentation.
Sarah Perez wrote a good article on Channel 10 about it:
http://on10.net/blogs/sarahintampa/Control-PowerPoint-With-Your-Phone/
I’ll post my experience on it within a short time.
How could I miss that… 
Read the next post here:
http://netindonesia.net/blogs/meidianto/archive/2009/07/09/control-powerpoint-with-your-windows-mobile-device-continue.aspx