Wind doesn't have contracts. The closest they come is with Windtabs, but if you leave before 3 years is up, you only have to pay off what's left owing on the phone.
Pay as you go is essentially just like everyone else's pay as you go plans.
The monthly plans are available as post-paid or prepaid. The only difference is that if someone with a prepaid account wants to use pay per use services, they need to have the funds in their account already, whereas post-paid accounts can pay at the end of the month.
Oh, and prepaid accounts can't have Windtabs.
A great wind is blowing, and that gives you either imagination or a headache. - Catherine the Great