Yep. Personally I have had no problems with the 75GXP, but I think it has a lot to do with keeping the drive cool (weird that tgillitzer and I were just talking about this).
You WON'T get a 120. And as tgillitzer said, if you ASK for a 60GXP you MIGHT get one because of the class action law suit filed against IBM for the failure rate of IBM hard drives.
To answer your original question: You don't need a receipt, just the manufacturer's serial number and a reason for return. Use the IBM diagnostic software to find a more legitamite reason for return. this will put leverage in your favor for not getting another 75GXP. If you call them and just tell them "the drive is bad", you will likely not get anything at all.