I'm replacing my laptop, a Dell Inspiron. I use the machine primarily for PowerPoint presentations with heavy graphics, audio and moving images. I typically build the presentations on my desktop (a PC) and then bring them over to the laptop. I'm considering an Apple laptop, but I need to know that my PP presentations will be 100% cross-compatible between the PC and the Mac. I don't want to build a presentation on the PC and then have to do a major overhaull just to run it on the Mac. Otherwise, I'll replace it with another Dell (and yes, I am limited to Dell or Mac). Any suggestions on a particular Dell replacement, and certain features, are welcomed.