solution for optoisolator 3.3 or 5 volt

Hello,
I'm building a bi directional optical isolator for a parallel port
and want it to work on 3.3 volt and 5 volt computers. If I run the
computer parallel port side leds and photodetectors off a 3.3 volt
isolated supply will it work OK on computer which have 5 volt
parallel ports?
cheers,
Denis