The IBM drive I RMAed was OEM, so I don't think it'll be a problem for you.
I called them up, stated that the drive was making clicking noises, and then they offered two forms of RMAing.
1. You send it to them first, then they send you one back after they've received yours.
2. They send you one first, and assume that you will send them yours. They take your credit card number, in case you don't ship it.
Method #2: the hard drive came in about a week later.