If you wind up waiting to buy a computer until after your trade show, I'd recommend the following:
Go to an Apple Store, tell them your needs and let them tell you if it's possible with a Mac. Hang out in the Store for awhile and play with the machines. I think you'll find that they're not as intimidating as you fear.
Go to Best Buy, or wherever, and explain to a sales person what you need. Let them recommend some Windows machines. See if you can hang out and play with the machines.
You do know that you can run Windows on Macs, don't you? Also, that Microsoft produces versions of it's productivity software for Macs?
The most important thing:
Keep an open mind and make an informed decision.