you're probably suffering from the binary to decimal conversion issue that has been much discussed.
1kb = 1024 bytes
1Mb= 1024 x 1024 bytes
1Gb= 1024x1024x1024 bytes
so 114Gb = 114x1024x1024x1024 = 122406567936 bytes
so yuo could write that as 122Gb on the advertising and the disk drive but when systems display it in XP, they will probably say 114Gb
Confused? You should be!