Many companies are currently considering whether to upgrade to Windows 7. Should you stick with XP a while longer? Wait for Windows 8? Plod along with Vista? Whichever previous Microsoft OS you're using now, there are serious security reasons to upgrade to Windows 7 sooner rather than later. Sure, Vista includes some of the same security features as Windows 7, and SP3 can make XP somewhat more secure (and the security updates will keep coming until 2014) but Windows 7 - especially the Enterprise and Ultimate editions - include security mechanisms that can help protect your network and more than justify the upgrade cost.
Read more about the top ten security reasons to upgrade in Lisa Phifer's article here: