George:

Thank you for your quick respond. I am suspecting that but because is XP I was hoping that the kernel32.dll is different and return values more accurate.

I check Cetin previous post and change my original code to the code used by Cetin but still get the same result. Also the Kb available does not match with the values reported by the operating system. Cetin formula report 15 mb and the system report 18.1mb ???

Anyway thank you so much