Well, the thing is, for someone who knows what they are doing, a "power user" The windows machine is going to cost less all the time. Consider... You can but a decent (ok, pretty damned nice) Dell system for $599. That gets you around a 2.4ghz machine, 256mb RAM, 40gb HD, a good solid video card, a 17" monitor and your keyboard/mouse, plus Winddows XP. You might even get a free printer.
The closest thing to that you're going to get from Apple is an eMac for about $800, and I believe that's only a 1ghz machine, so it's about 30% slower than the Dell.
All your additional software is gonna cost the same between the two machines... And if you stick with good name-brand accessories, they'll all cost the same.
If you keep up on your maintenance, defrag the drive once a week, keep your virus definitions current and your OS revisions current, the machine will probably not break down.
Hmmm.... All in all I guess it works out about the same... Not the road I was going down when I started typing this, but I guess it works out... Where the big hits come in is if you want the high-end machines... Then PC will definately be cheaper hardware wise, but you'll get more performance from the G5.
Ok, I'm blathering and lost my train of thought... It's time to go home... Maybe I'll re-write this more coherently this weekend some time.
Jerod