copying projects from one OS to another

Hi

I have some ASStudio applications that were developed under OSX 10.4 and I want to move them to OSX 10.5, if I copy them over manually and open xcode I get a message saying that:

Unable to Open Project
Project /Users/develop/Documents/SCRIPTING/SCRIPTS:APPS/BEER/BEER.xcodeproj cannot be opened because it is missing its project.pbxproj file.

so the question is, how do I copy my project from one OS to the other without this issue occurring?

any ideas?

I found a way using CCC (carbon copy cloner), probably a correct way, but this helped.