Flyswift, I'll leave it to the boffins to offer an opinion on technical merits, but I when I was thinking of replacing my poota last time I considered an iMac. In short, the problem was software; mainly the amount of new programs I would have to buy, plus the data I've accumulated over the years; spreadsheets, databases etc. that wouldn't convert easily or at all.
It appears once Mr Gates gets you, he has you by the short and curlies