Hello,
Your problem is the way windows views the hard drive. 298GB is about correct for a 320GB drive. You have to multiply it out to see the correct number.
298.9 X 1024 X 1024 X 1024 = 320941431193.6
320,941,431,193 Bytes or 320 GigaBytes
298.9 times number of MB in GB, times KB in MB times KB in B. When the format is done and you look at the drive properties you will see correct number of total bytes.