Nah it doesnt have anything to do with php5 , The zip_open function that gives you the error has to be compiled into the php/apache core, When i wrote the installer i tested it on three machines with different hosting companies and assumed that most hosts did this by default, im currently working on a fix and should hopefully have something in the next couple of days, I'll forward it to MrZero when i have the fix so he can forward it on.
Them being on your old board wont make a difference as a zip file is a zip file regardless of php/vb version