Do a search and you will find a bunch of information.
You can certainly use Arimidex instead, and if you can afford it, go ahead and use it throughout your whole cycle.
Benefits of Arimidex far outweight those of Nolvadex, including the fact that you can stay on ADex the whole cyce while not inhibiting your gains, and cutting estrogen (reducing gyno) aromitization consistantly at the same time.
If you can afford it, go for it. Only use Nolva if you notice signs of gyno. Other than that, don't use it.
SemperFidelis