VS 2010 possesses a totally different MSBuild-based build system for all provided languages and so build box may not have Visual Studio installed at all. It will be developed further and it means you will have to upgrade your VC++ project sooner or later. Sooner is usually cheaper.
It's greatly integrated with TFS so that many tasks, SCM, build, teamwork, testing, unit testing, publishing testing results can be done in a smooth, more convenient way.
During changing VS editor, engineers took into account many common developing scenarios and shortcuts in order to make a developer as much productive as possible. A set of code snippets is just must-have. Many lines editing feature (Alt-Shift) is now a common scenario for me. IntelliSense finds the best code completion than ever and supports C++ better (or at least got crashed more lately).
.NET 4.0 has many good features too like dynamic, MEF and tuples. They're nice and when you get used to them it's hard to live without the things.
Commonly used projects may be exported as project templates.
One more thing, there is a build-in extension (plug-in) manager with online extension gallery with a lot of useful plugins (Productivity Power Tools, Code Map, Block highlighter etc).
Performance analyzer and code analysis are really good. Class diagram started actually working with C++ code.
Last but not least, VS 2010 has full screen view to code without distraction.
I hope you find something here to back up your idea.
VS2010 has the only drawback, it's slow. Therefore, the developer machine should be based on Nehalem processor core at least and has got 4Gb memory. You are warned.