Just install Vista Business with the VL key. No conversion necessary. Only Business from the ISO supports VL (the other is Enterprise but that's a separate ISO).
Thank you very much for quick answer - Will this key activate business version? I installed home premium at the desktop comp. of my son, and i can not activate it. i used kms auto net, microsoft tool kit and kms vs all, but none succeed to activate it. I have read that vista business is vl which i guess those activators will manage to activate if not vl key. am i right?
Only Business and Enterprise even have a VL channel. Home Premium does not, and thus cannot be activated by KMS. The gVLK will turn Business into a KMS Client machine. It will not activate that machine by itself. You still need to use a KMS solution (MTK etc). Note that most solutions should already apply the correct key for you.