Customise the log-on screens in Windows 7 by using this 'how-to' guide.

Also I found out how to add your own channel logos to Media Center on Windows 7

Get up to speed with  BitLocker To Go using this  Microsoft TechNet Edge video - it shows you what to do, and explains how you can recover lost keys and what happens when you share with someone who doesn't have Windows 7

If you want to know more about Windows 7 then the UK DPE team have done a bunch of videos under the banner of YingYang such as YY: Introducing Windows 7 and Windows 2008 R2 . I also made note from a TechNet newsletter about Windows 7 Upgrade Paths -  Check out this quick table reference. Its worth checking the Podcasts too:

Windows 7: Increase Productivity, Improve Security, and Streamline PC Management