I think the issue is vista 64. I gave up and don't use vista 64 because of network traffic speed and priority issues among many other reasons including digital driver signing.
Do you have SP1 installed? Vista 64 plays network speed games with something called MMCSS (Multimedia Class Scheduler Service). There are ways to modify how MMCSS works with registry tweaks once you have SP1 installed. Google it. Don't know if that is root cause for you, but when I had tons of issues trying to stream video in vista 64, I concluded it was. No such issues with vista 32 or XP.
IMO, there really is not any reason to run vista 64 - I don't have a single program that is written to use 64 bit and most all software does not take advantage of it. Vista 32 works fine - 64 is a nightmare.
I'll bet the 160 works fine on XP or vista 32. I have a 642 card and it works as it should on XP.