Lenovo S10-3t, touchscreen tablet netbook. 10.4" multi-touch screen running Windows 7. Less than a year old, bought from Best Buy, then upgraded with extra memory and a lot of software. Was used for browsing the internet and for mapping in my car, has been all over the place, and has plenty of mapping software for your expo needs 
Hardware Specs are:
Intel N450 processor, 1.6GHz
2 GB RAM
250GB Hard Drive
2 USB
1.3MP Webcam
Included bluetooth dongle (USB)
8 cell battery (easily 6 hrs on a charge, 8-10 if you go to battery saving mode)
Software
Windows 7
Office 2010
Garmin Mapsource + North America Maps + NOAA Maps
Garmin Mobile (for in-car navigation)
Delorme TOPO 8
Delorme Street Atlas 2010
Delorme Street Atlas 2009 plus (includes business listings)
National Geographic Topo (with Washington, Oregon, California, Idaho, Alaska maps)
...plus a whole ton of other software...
Asking $400 OBO
Hardware Specs are:
Intel N450 processor, 1.6GHz
2 GB RAM
250GB Hard Drive
2 USB
1.3MP Webcam
Included bluetooth dongle (USB)
8 cell battery (easily 6 hrs on a charge, 8-10 if you go to battery saving mode)
Software
Windows 7
Office 2010
Garmin Mapsource + North America Maps + NOAA Maps
Garmin Mobile (for in-car navigation)
Delorme TOPO 8
Delorme Street Atlas 2010
Delorme Street Atlas 2009 plus (includes business listings)
National Geographic Topo (with Washington, Oregon, California, Idaho, Alaska maps)
...plus a whole ton of other software...
Asking $400 OBO