Guys I got it:
1- My operating system is Xp home edition on "A" and i log in to the system without a password so i had to give that username a password.
2- In IIS right click on the computer name web site and go to properties/Directory security, click on edit, then Edit, Pick the XP username and enter its password. Press OK.
3- same goes for the default web site and virtual directory, but in the virtual directory's security tab click Edit and uncheck "Integrated windows authentication" and VOILA.
Dany K