And that is why you go prepared and cover all options:
1. PowerPoint (on four different media typea, five different cable types and a spare laptop).
2. OHP (along with suitable OHP).
3. Flipchart (along with a flipchart stand).
4. Laminated, sticky labels (with green felt board for attaching to)
5. Chalk and board (with suitable big duster)
That about covers all the bases. Only downside is your prep and rehearse time is now so long the vacancy will have been filled before you've finished laminating the last label.
You forgot white board pens and an eraser.