The only suggestion I can give you here is: PREPARE!
Not trying to be funny, but only go out with gear you know and have tested. Otherwise you are setting yourself up for potential disaster. I have been doing this for a VERY long time and figured the rule didn’t apply to me. I was doing a benefit for “my” local American Football team, playing music during warm-up and the game. I took some gear I hadn’t used before and ended up not using it at all as I could not get it to work the way I wanted. Luckily I DO prepare, so I just tossed my Numark iDJ Pro with prepped iPad on the stand, hooked up the speakers and was off to the races. Without that, I would have stood there like a total twat 😀
On normal gigs I will have my regular MacBook with me AND a Dell Win7 PC. Both are fully tested with both my controller and the external harddisk I use. So, if something happens to the MBP, I’ll play from one of my CD players (which I always have hooked up at a gig – being a mobile DJ and all) and swap the laptop in the meantime. About 5 minutes after that I have the 2nd laptop working and it’s back to the controller and Mixvibes Cross.
Greetinx.