This hard drive from Western Digital has room for 750 GB of data. The form factor is 2.5" which apart from this model is commonly used in SSD drives.
AA2Z Supply
WESTERN DIGITAL WD7500BFCX WD RED 750GB 5400RPM (INTELLLIPOWER) SATA-6GBPS 16MB BUFFER 2.5INCH INTERNAL NAS HARD DISK DRIVE. BULK. .