Thank you leogc,
Ive logged in and it synced everything back to my browser, exept for the open tabs wich i had around 77 of them. But as i'm used to format my computer very often, I've kept a backup image of my old windows installation.
Because I do not know a better way to restore everything as is, here is what I've done:
First I made a backup of the folder named ''Opera Software'' in the %appdata% of the windows explorer
Then installed opera in the new computer, and runned it once in order to create it's folder in the \AppData\Roaming directory.
After that it's easy to crush that folder with the backup made earlier.
And finally login to sync for restoring all the saved passwords.
But for the sync part, it is not very obvious to kinda guess if I log in, if they will overwrite the old backed up stuff or to restore my data. Maybe it would had saved me some worries if it were a clearly shown button to give the choice to either overwrite, merge or restore the data saved on the sync server.
What do you think?