Here is a very well written article describing why Microsoft won't attack non-Novell Linux.
http://blogs.zdnet.com/carroll/index.php?p=1617
From the article:
"A Microsoft that goes after Linux on the basis of patents opens itself to countersuits by companies with an interest in Linux and patents which can be used against Microsoft. Nobody has more patents than IBM." I still can't help but distrust the situation.
