Is a Unity project portable?

I created a Unity3.5 project on Mac. After copying it to a PC, Unity doesn’t see all the assets in it even after a menu refresh. Is such a project portable across PC/Mac, or do I have to do something special to make it happen?

Also before I tried to remove Assets/Library/cache, but that instantly killed the project.

Yes I do this all the time - you have done a reimport all assets?