Doug Cook, a member of the Platform Builder team, wrote a post on this topic here: http://blogs.msdn.com/dcook/archive/2007/05/13/does-pb-5-0-work-side-by-side-with-pb-6-0.aspx

Posted by Kurt Kennett The Windows CE Operating System is composed of many modules. Some modules are interdependent on each other. Most modules never need to be touched in order to provide the desired functionality. However, there are some cases where it is desirable or necessary to replace some default...

Posted by: Sue Loh Note: Big thanks to Jonathan Lyons who is the true author of most of this post! Italics are my writing, the rest is his. Jonathan is a program manager on the Windows CE tools team, and the speaker for the “Windows Embedded CE 6.0 Tools” on-demand session at today’s CE6 virtual launch...

Posted by: Sue Loh If you have just done an install of Platform Builder, and opened it for the first time, and seen this dialog box: (here is the text, to make it more likely that someone can search the web and find this article) The setting for the Platform Builder global WINCEROOT is missing...