Here's my two cents... you admit you need a new computer. You know you're going to have to buy one anyway. You're dealing with a lot of stress in your life right now, and this trade show is very important to your business.
In my head, this is the simplest 30 minute errand run in the world.
Step 1: Stand up. Walk out of McDonalds.
Step 2: Drive to computer store. Buy new laptop.
Step 3: Live life stress free and much more happily.