One thing I thought I'd mention, the CV64 has way better picture quality than the CV643D, I switched my CV643D to a CV64 mostly because of the picture quality and also because it's faster. The 3D part of the CV643D really sucks and you can use the CV643D scandoubler with the CV64 card (if you own an A4000 as I do that is pretty nice).
Only reason I see for getting a CV643D instead of a CV64 is that they're usually cheaper.