"Pre-Encrypt" a laptop

Does anyone know of a way to pre-encrypt a laptop before the first client enrolls? We are preforming Windows 7 deployments and our biggest complaint is performance (specifically HD performance) on laptops while they are encrypting. If possible we would prefer to have the laptop hard drives already encrypted or at least started before the users logon for the first time to ensure the best experience possible. 

Any help would be greatly appreciated. 

Kraag