Ellen Finkelstein has a great post on disabling the pop-ups on your computer before you give a PowerPoint presentation, as some of these little reminders might appear right in the middle of your talk.
I suggest going a step further and setting up a separate profile just for your speaking engagements.
When I take my laptop to a venue, I use a profile I've set up, called "Presentation," which has a link to my PowerPoint on the desktop and nothing else. There are a couple of program shortcuts I haven't figured out how to get rid of that show up on all of my profiles, but that still leaves me with only four icons on my desktop, instead of 30+ on my regular profile.
Also, my IM login, my Skype login, and other programs that automatically load on startup in my regular profile are not there. This resolves part of the issue in Ellen's post about programs popping up or someone sending me an IM in the middle of a talk!
The profile loads faster, and there's no need to dig around looking for the presentation; it's the only file on the desktop.
Check out Ellen's post for the how-to on keeping those pop-ups down.