The virus wouldn't have worked, once a cube is infected with anything that could or might threaten the Collective, it's cut off from the Collective. End of problem. As could be inferred from Hugh's cube, it was cut off once Hugh's individuality "infected" the rest of the cube. As stated before, the attempt at infecting the Collective with a virus could have made the Federation more of a threat in the eyes of the Collective.
One last question, if the virus was one that the Borg would have concentrated more and more processing power on as they tried to figure it out, why didn't it cause Data to go out?