Bizzare thing happened after i compressed my windows XP partition .... Instead of Used space decreasing it actually increased by 1.5GB !!!!
Then after a reboot it became 1.5GB lesser than my first Used space value ... Now its compressed ....
i have observed one more thing if you compress a software or a game folder .... The reduction is very large ... But it is not that much for audio vedio files .... It is hardly any compression at all