The short story:
VS2005 and VS2008 will not co-exist peacefully.
The long story:
After several fruitless days trying to create an environment for developing an application for the Windows CE 5.0 platform using Visual Studio 2008, I had to admit defeat. The reason is, when Visual Studio 2008 is installed on a system that has Visual Studio 2005 already, it clobbers the Windows CE 5.0 platform so it cannot be used by either IDE. No complaints, no warnings, just gone.
Microsoft contends that VS2005 and VS2008 can be installed and will work side-by-side. What they did not document - typical for MS - is that certain platforms not only are incompatible between the two, but are also disabled for both. The Standard Windows CE 5.0 SDK is one of those platforms that is disabled when VS2008 is installed. I haven't had time to find out what additional platforms may be affected.
It's not an operating system issue. I develop on a Windows 7 machine. My co-worker uses Windows XP. Both of us experienced identical problems.
My objective was to install VS2008 to work on a project I had inherited where a back-end database application had already been written as a VS2008 project. I wanted to create a Windows CE 5.0 application using the same IDE. Silly me, always expecting "new and improved" tools to work as advertised.
VS2005 with the Standard Windows CE 5.0 SDK was already installed and working fine, as I had just completed another project with that exact combination. Install VS2008. See Windows CE 5.0 platform disappear. Did installing with Administrator Privileges work better? Nope. Uninstall, reinstall, uninstall, reinstall without Documentation = No joy. Jump up and down on keyboard, smash fist through monitor, throw laptop through front window - *sigh* just wishful thinking.
Last resort, uninstall VS2008. Gee, that worked; now I had my Windows CE 5.0 platform back in VS2005. So I couldn't use VS2008 for my new project. In summary, VS2005 and VS2008 can co-exist, but only if they are on separate machines. :-/ I was burned by Microsoft marketing hype yet again.
And they want me to upgrade to VS2010. Hahahahahahaha!