actually yung sinasabing 40GB is an approximation. the exact is not really that
ganito kasi yan, 1 KB is not really 1000 bytes. its 1024 bytes. so yung memory mo na 256MB ang report ng windows is something like 262144 (tingnan mo yung memory test sa start lampas yan ng 256)
yung sa hard drive naman, kaya less than ang nakikita mo kasi yung advertise ng manufacturer na 40GB is only 40,000,000,000 bytes not the actual 40GB (which is something like 4.096 billion bytes). so yung 40,000,000,000 bytes na yan is only around 37.25 GB