Yes that's quite normal, and it has nothing to do with formatting or partitions.
It's simply that the drive manufacturer's use the decimal formula 1000 bytes = 1 kilobyte, which is technically incorrect. The correct formula is 1024 byes = 1 kilobyte, and that's what your computer uses to calculate the capacity.
So when you think you are buying a 320GB hard drive, you are in fact buying a 298GB hard drive.
None of the drive manufactures want's to be the first to use the correct capacities because then the buying public would think that particular brand of drives was poorer value for money.