How could the hacker transfer the money ? I had the wallet secured by a password as well ?
This is quite easy if the attacker had a keylogger installed on your system. A little patience and sooner or later he would see you typing in your password.
Yes probably a keylogger, try to run a virus scan because the keylogger/virus could still be located in the hard drive. Be more careful on what you download in the future. Good luck !