Most DC motors need a much higher rpm than possible with a windturbine. Max safe speeds for turbines are ±500rpm, but usually less than 300rpm. So you may need a gearbox.
Only way to find out for sure is to put the motor on a bench, and test the output against know rpm's.
A DC motor which for e.g. does 3000rpm at 24V, if turned at 500rpm will make about 4V. Gearboxes (or pulleys) are a bit of a pain to make, and also lose a lot of energy. The gearboxes on large turbines is apparently the most technically challenging component, the most expensive, and requires the most maintenance.