Every few years you hear that this version of Windows is "the most secure ever". Now that statement has always been true to the time when it was made, but with Vista things just feel a little more secure. There are a host of new security features in Vista such as Bitlocker, UAC, NAP client, Windows Defender this list goes on. Understanding how these tools work on their own and as part of your overall security strategy can be a little overwhelming at times. To ease this and to get you running Vista securly some kind folks in Redmond wrote the Windows Vista Security Guide.
I've taken a quick look over the document and it covers quite a bit. Baseline security, malware protection, IP protection, application compatability and more. One of the really cool tools is the GPOAccelerator.wsf script. The tool enables you to run a script that automatically creates all the Group Policy objects (GPOs) you need to apply this security guidance. The Windows Vista Security Guide Settings.xls file that also accompanies this guide provides another resource that you can use to compare setting values.