projector advise please!

[chrbb]

Warning on ancient askproxima projector today lamplife expired (although it still works) despite finding required replacement lamp on various websites not in stock, neither can anyone get one.
So new projector required - looking closely at ancient model it has a computer input and a monitor output - understand these two, but there is also a psp mouse cable attached to the computer data source cable, also audio. Are these really required? we have speakers attached to the computer and an interactive smartboard, what does the mouse attachment do on the projector?
Cheers

[plexer]

With some projectors you can use their remotes to control the computer as if it were a mouse. So the projector would send the signal to the computer via the usb cable and the computer would see it as a usb mouse.

Ben