"Presentationzen" by Garr Reynolds and "Slide:ology" by Nancy Duarte will be exceedingly helpful to you. Here are links to their blogs and Amazon descriptions. Good luck!
You should also find a copy of Guy Kawasaki's "Reality Check" or "The art of the start". Even if you don't have enough time to push through the whole book, just read the chapter on pitching. Should be very helpful.
http://www.presentationzen.com/presentationzen/
http://www.amazon.com/gp/product/0321525655/103-6148611-3957...
http://blog.duarte.com/
http://www.amazon.com/gp/product/0596522347?ie=UTF8&tag=...
You should also find a copy of Guy Kawasaki's "Reality Check" or "The art of the start". Even if you don't have enough time to push through the whole book, just read the chapter on pitching. Should be very helpful.