Our one and only enterprise application suite has been developed over last 3 years using C# 2.0 on .Net 3.0. We use winforms and WCF heavily. The development tools is VS 2005 Pro / TFS 2005 / Resharper 3.1 As technical lead I obviously understand the benefits in a move to C#3.0 and .Net 3.5. But I want to convince management for a move to C#3.0, .Net 3.5, VS 2008 and TFS 2008. They will obviously be interested in things like productivity, cost, quality etc. Please suggest me some ideas on how best to make my case. Given that this may not happen till mid next year am I better off to hold till VS 2010 and .Net 4.0 is out.