Here's the quick rundown of what it is we're trying to accomplish: we sell, in addition to physical products, access to an online user area where the user must set up their account via a link given to them. The link varies depending on the type of account they purchase, so I'd like to have some way of directing them to this particular link directly after purchasing. (right now, they have to wait for us to send them an e-mail. Many people don't want to wait this amount of time.)

How would I go about doing something like that using Product Types? Or would it be done with attributes?