32 spoke/hole wheel will hold heavy riders just fine, but you don't need to worry about that. My commuter has 24 spoke wheels, and I weigh 265lb and carry a bike trunk & panniers that probably weighs 10+lbs packed, and have only trued the rear wheel once, when it was out of true by less than 1mm in one spot.

The less spokes/holes the wheel has, the higher the spoke tension will need to be in order to keep it true. Higher spoke tension means you need quality wheel components. But the difference between a 32 and a 36 is negligible. 36 spoke wheels are still very common - if you're shopping for a bike at Wal-Mart or Target. Otherwise, 32 and under is pretty much standard now-a-days.

If you're re-using your old hub, then you'll need to get a rim with the same number of holes that are on the hub. You'll probably also need to buy new spokes, since the old spokes probably won't be the right length.