I've found some funny effects (actually, just Monday, when I had to scramble to re-make the missing elements
) with pasted pictures in Powerpoint going between Mac and PC.
I wrote my presentation on my Mac, and I copy-and-pasted some web graphics -- all jpgs or maybe a gif or two that I stole using google images
-- into my presentation. Also a picture that I copied out of a PDF of a journal article using Preview. And three Excel charts, which I pasted in using enhanced metafile (paste special).
When I opened it on the PC, some of the graphics came up as boxes with something like "unrecognized quicktime file" in them, as did the Preview object, and one of three excel charts. Everything else imported fine. The excel chart was the big headache because I didn't have the original with me when I got to my office, so I had to re-do the chart from a paper copy!
Anyway, about a half hour devoted to rebuilding my presentation instead of surfing.
But not too too bad. All the formatting and stuff came out fine.
As far as Powerpoint on Mac vs. PC, I agree that for anyone who has "mastery" literacy on a computer, going back and forth is a non-issue. There are minor things I've had to consult help on, since I got Office.X on my Mac in December, but very rarely are they mac-specific issues. But if you've learned to do complicated things, and you really only have surface understanding (so you just memorized a set of instructions to get your effect, but you don't understand them intuitively), I guess I could see how Mac and Windows office seem very different.....