Have a computer hooked up to a projector where everyone can see it to do examples on. Get a decent stock of Live CDs (and a couple USBs for netbooks) and have volunteers to help install and configure Linux on peoples computers or just answer questions for people tinkering with the live discs. I have a file server that we can use to do backups of photos or documents people can't afford to loose in case a partition shrink goes wrong.
This will be the main "stage". Instead of having set presentations for this area I'd rather leave it open to the request of the guests.