Do I need an upgraded alternator?

I have 2 500W amps in my car. One powering the sub, and one powering the 4 speakers. The voltage in my alternator broke months ago, and the rest of it followed last week. So, I need to replace my alternator.
My question is, will a factory spec alternator be able to reliably put out the power I need, or should I get an upgraded/overspun alternator?

If you can it is best to upgrade you power system anytime you add additional load to your factory system. Now is it required no but it is a good idea.