There are also litteraly over a thousand different Microsoft newsgroups. My newsserver carries over 1,700 Microsoft groups.

They all start with microsoft.public.topic where 'topic' is replaced by the application or operating system you're interested in. For example Windows alone has hundreds of different groups, Word has over a dozen, with nearly every Microsoft product represented.

The newsgroups can get noisy, and there is a lot of ranting typically, but still a lot of knowledgeable people hang out in such groups including some Microsoft engineers, so sometimes worth the effort wading through the excess noise. If your ISP doesn't carry Microsoft newsgroups directly, (most do) you can point your newsreader directly at one of Microsoft's news servers.