The new version 4.56v updates the AGP driver to version 4.43f. The new AGP driver simply includes new IDs for new VIA host bridges. So this driver update is not really very exciting to be honest. In fact there isn't really any reason why you would need to update your system with them. If it ain't broke don't fix it. But if you are building a PC or you haven't updated in a while then these latest ones are the ones you should use.
Download: Download Page
News source: VIA Arena
