Hard disk memory full

hi guys , I have ASUS Eee PC 1001PX , I have 75Gigabytes size per hard disk with a total of 150 Gigabytes because I have two hard disk , please help me my hard disk is now full . I didnt even know why , I dont have any files on my hard disk but it shows memory full , I cant paste my files now , what should I do ? im using Windows 7 professional and I dont have DVD rom,

You should check to see if the system backed itself up. Sometimes the system makes a copy of itself and doesn't let you modify it. Try searching for that option in control panel....or whatever it's called in Windows 7. If not you can always reformat. :)