That's from my experience, speakers
1) often want to use Powerpoint in Presenter mode, which means the laptop location has to be thought out
2) want to use their own laptop which might be a different resolution and might not be hdmi (adaptor needed)
Buy a copy of Office 2010 for the laptop at £20. I bet at least half would prefer to use Powerpoint, even more when they know it is easier to use than a smartphone.
Make videos in Picasa is an option. Timed sequence of still pictures.
The tricky bit is compatibility between laptops and...