Final Cut Express 3.5 project to Final Cut Express 4
Well, now that I have FCE 4, I can answer this. Yes, you can open an FCE 3.5 project in FCE 4. But when you open the FCE 3.5 project, you will be asked to save it in an FCE 4 compatible project. This means that you will be left with two files, an older file that can be opened in FCe 3.5, and a newer one that only can be opened in FCE 4.