I am comfortable using visual studio in 2005 version because I still use windows xp but whatever projects made on 2005 version they are not compatible with the 2012 version where I do projects in office. Once a old version is tried to run on a new version, the new version just makes a back up of the old one and donot even show the code to execute and when you work in a new version visual studios.
When you use those files in old version, it will show unknown version and would not start up. This made me face alot of problems. Microsoft should build as all the old versions should be compatible in the new versions.