Also, there's a discrepency in sizes between memory and hard drive capacities. http://en.wikipedia.org/wiki/Gigabyte

Hard drive sizes are in decimal sizes, whereas memory sizes are in binary sizes. ie, a 1 gigabyte harddrive has 1,000,000,000 bytes whereas a 1 gigabyte memory stick has 1,073,741,824 bytes. We all get silently robbed by the hard drive manufacturers :)