Just a guess here, but it seems like Microsoft's move to deliver their OS digitally opens them up to some malware problems. A hacker could sneak their malware into this digital download process, maybe mid-stream or through phishing scams. Both of which are potential new problems with delivering them over the internet. I suppose Apple faces the same problems too, but less so because their system is a bit more closed.
11/22/11 at 12:48pm