Is Windows Vista the lowest cost, most secure, most intuitive, most manageable, most entertaining and therefore the best operating system Microsoft has ever produced?
Now before you answer the question, consider how well Windows XP has done. Windows XP is rock solid. The security for Windows XP and IE have been dramatically improved since it's release.
Have you tried Windows Vista? Are you planning on buying it on Tuesday? Are you waiting and getting a new computer with Windows Vista on it? Which version are you interested in? Why? Why not?