I don't think any hard drive manufacturers have any qualms about transferrance of warranties. In fact, I'd say that the only times manufacturers stiff you out of a warranty is if the drive came from an OEM like Dell, Gateway,etc.
I don't think any of them ask for a receipt or anything either (I've only had to provide one once, for a Quantum Fireball+LM, before Maxtor absorbed them, and even in that case it was only because the serial number was strange and wasn't coming up right in their database (It happened to be a drive from Buy.com)).