<p>As of the fall of 2008 I'm about to embark on a new development cycle for a major product that has a winforms and an asp.net interface.  We use Telerik, DevExpress and Infragistics components in it and all are going to have a release within a month or so which will be the one I target for our spring release of our product.  </p>

<p>They all support VS2005 and we will continue to target .net 2+ so I can't see any compelling reason so far to upgrade to VS2008.</p>

<p>Has anyone found a compelling reason for upgrading to VS2008?</p>

It's worth it. It's faster, the designer is vastly improved (split view, faster context switching), it has better support for javascript and when you're ready to target 3.5, you'll be ready to go.