I want to put Final Cut Express on my 2007 Macbook so I can get a bit of simple work done while my main computer is being fixed. Can I open projects in FCP 7 - what I use - in Final Cut Express to work on them?
No sadly you cant open FCP projects in FCPE - you can the other way around but thats no good for you.
Since you are permitted to make a "machine readable back-up" - you could perhaps reasonably argue this is a temporary back up installation and install on your laptop - its not like you can run them both at once since your main machine is away being fixed.
Maybe for speed just load FCP (rather than the whole Studio) to enable you to carry on working while your machine is repaired.
Just make sure you delete the laptop install once your main machine is returned if you want to stay legit.