A great place to learn the basics. The Vista entry includes a wealth of background and information, as well as images and screen shots. Wikipedia provides a good overview of Office 2007. The Exchange 2007 info is sketchy; skip it.
Ed Bott's Blog
Author of more than 25 books on Windows and Office, Bott covers Windows, spam, and Office, proffering snarky comments about tech culture.
Building A Mobile Business MindsetAmong 688 respondents, 46% have deployed mobile apps, with an additional 24% planning to in the next year. Soon all apps will look like mobile apps – and it's past time for those with no plans to get cracking.