In that case, i'll buy the 4850. But I still have a question:
I used to own a (broken) 4850 that, besides being damaged, worked perfectly in my pc with a 420w psu, it never shutted down or something, just a bit more intense noise. But I've read that the 4850 requires at least a 450w... So, should I buy a new psu, even though the graphic card works well in my pc?