[Axo]

Since i had created a 10GB partition for XP and Vista by itself eats more than that, i tried to delete the partitiont trough Bootcamp assistant and to create a new 20GB one. No way. The disk seemed to keep a trace of the previously created partition and then bootcamp refused to install any partition whose size was different from 10GB. I had to clone the whole hard diskon my external drive, erase the internal HD, and then cloning back the disk. Only then bootcamp managed to create the partition i needed.

[Cold Warrior]

You could have used bootcamp to restore your drive, thus sparing you from erasing the entire internal HDD, then used bootcamp to create a new windows partition.

[Axo]

This is what i did at my first attempt. But even if the partition seemed to have been erased, something remained since i was not able to set partition of any size except of the one of the previous partition