I'd go for PIV. It has better picture quality than CV3D, IMHO. And AFAIK it's bit faster and has nice bonus features like built-in scandoubler/flickerfixer, addon-options, possibility to add frequency of video-modes etc..
CV3D is nice for "cheap" gfx-card, but lacks bit in speed and picture quality and 3D features are useless in practise. And scandoubler addons are quite rare for it...
