How do you perform large PC rollouts?

As more of a survey than a question, I am curious how others perform large scale rollouts or PCs (laptops and desktops).

Specifically I wonder if you:
1. have PC vendors load an OEM image
2. reimage using a Ghost type product
3. use a Desktop Management system (which one)
4. other.

I/we are struggling with what is the best way for our organization to do this.