i just got my ibook933 6 weeks ago, and i love it so far. i'm a techie guy, and i'd used OS7-8.6 in school. and then i'd had limited experience with OSX. i was a little worried about the learning curve myself, but i was willing to risk it for the advantages (power, longetivity, BATTERY LIFE--5 1/2 HOURS?!) that i saw over the PCs i was so devoted to for my entire life.
my own experience is that you get used to the mac way of doing things really quickly. in fact, within 3 weeks, i found myself dragging my mouse to the corners on windows computers, and trying to use alt+c/alt+v to copy or paste. i can't even count the number of times i've tried to close windows using alt+w.
there are things i miss, like a right mouse button. i have a two-button mouse at home, and when i'm on the road, my control key and i get to be good friends. if i may, OSX is a lot less mac-ish than the older OSes...partially due to the un*x elements in it. so familiar things like file extentions are there to greet you.
overall, you'll have a pretty easy time if you spend a day or two exploring. and as an IT guy, i know you will! 😀