I use PC's all day and Mac's for fun. I also do a bunch of stuff on my friends PC's and the one thing that absolutely blows me away is what a pile of steaming junk IE is.
Trying to do stuff results in pop-ups, porn ads and spyware. It's amazing. I use Firefox on my PC at work and totally forgot how bad IE is.
Of course, this is not just a result of IE being a lousy browser, but the huge amount of plain junk out there for Windows. I seriously hope Apple doesn't ever get that kind of market share.
Cheers.