Sun's approach in targeting different device 'profiles' with the Java EE, Jave SE, Jave ME etc. made the JavaVMs quite light weight in smaller devices and feature rich on enterprise servers. Microsoft .NET has had a similar approach with the standard .NET framework for full-fledged computing devices and the .NET Compact framework for embedded devices (PDAs, smart phones and their cousins).
With .NET 3.5, Microsoft has branched out the standard .NET framework into a full package and the client-only subset. The client-only subset is targeted at Windows XP legacy systems on which .NET 3.5 client applications need to be deployed via the web so if you're running Windows Vista you've already got the full profile pre-installed with the O.S.