Most gingers do go dormant so it's best to let your's go dormant since you don't know what they are. Keep barely moist over the winter. When you see new growth give more light and water.
Check the sight below and you may be able to identify them.

Here is a link that might be useful: Ginger info

Do I actually take them out of the soil, wrap in moist newspaper and keep the out of the light (like you do with bananas), or do I simply put the pot in the garage and make sure the soil doesn't completely dry out?

Thanks again.

We never took ours out of the pots when we overwintered gingers in NJ- just stuck the whole pot in the basement, occaisonally watered and waited until spring. In the spring, we moved then outside, into the shade first, to slowly acclumate them to the sun.

In terms of "letting them go dormant" or not, you don't have much choice. The species that naturally go dormant will go dormant, and the ones that don't won't. But without knowing what you have it will be a guessing game at first. I would keep all of them moist while they are still green. Some or all of them will at some point start dying back. Those are the dormancy requiring species. Cut back on the watering for them (don't let them completely dry out, but don't let them be wet either). The evergreen species will probably start looking more ragged but will stay green. Keep them moist but realize that they won't grow much in the winter, so don't overwater them either.

If you can determine what kinds of gingers you have you may be able to plant some of them in the ground next year and leave them permanently outdoors. In fact, if you want to expand you ginger collection you are in the ideal climate for growing Roscoea, a high altitude Himalayan ginger. The Pacific Northwest is the only area in North America that can easily grow that ginger. Might be worth a try.

-Kyle