If you are like most IT managers in a midsized shop, you probably skipped Windows Vista. Winodws XP probably still serves your needs well. While it is true at some point you may start hitting compatibility issues wherein software updates for XP will cease, but that is likely a while away given the massive install base of XP. While your end users likely demand new features in Office, driving an upgrade to Office 2007, users care less about the underlying operating system, as long as it is stable. So, give me one good reason to move my enterprise to Windows 7, right? OK, I will give you four.
OK, one of the first things to realize when talking about new features in Winodws 7 is that most of them depend on new features in Windows Server 2008. BranchCache is a great branch caching tool to speed up access to content to field sites. It can work in two modes, distributed or hosted. But don't believe me, watch the video.
DIrectAccess allows mobile users to connect to business resources without VPN connections. This is similar to the functionality provided by RPC over https for Outlook or an edge server for Office Communicator. This is driven by a certificate architecture and is heavily dependent on new features avaiable in Server 2008. Check it out.
BitLocker to Go
BitLocker was introduced in Winodws Vista and improved on in Windows 7. BitLocker allowed you to do full disk encryption on laptop or desktop drives. BitLocker to Go introduces the ability to encrypt USB drives and even lets you enforce your USB encryption policy through the use of group policies. Very cool.
Enterprise Federated Search
Winodws 7 enhances the desktop search capability to incorporate searches for unstructured data across and outside the enterprise. Prebuilt connectors to SharePoint 2007 make this a really cool feature.
There are many other improvements and new features in Winows 7. Here is a one page chart that compares Windows 7 features to those in both Vista and XP. It seems clear to me that Windows 7 offers enough benefit to make the change in the enterprise. Keep in mind however that many of the new "Windows 7 features" really become available once you implement Winodws server 2008 so, start planning....