Good luck with that, Vista is so new and no service packs available so there's tons of issues people are seeing when deploying on company networks. I'm waiting for a service pack before even thinking of deploying.
If at all possible, ditch the 705. It's an ancient piece of hardware. The SNAP OS is outdated and has issues with 2003 domains.
We're having the same trouble here. Fortunately we have just a couple of Vista clients right now. Has anyone come up with a workaround or a solution for this? It seems quite odd to me that Vista users get "Access Denied" when trying to access files on the Powervault 705N. Well maybe not odd, but certainly frustrating!