The card has PureVideo support, but sadly, Nvidia will not support it on Linux. As for the 64-bit flash linux player beta, here is the link:
While I have not double checked, that is where Gentoo Linux's package manager downloads its plugin and I do not have nspluginwrapper installed on my amd64 desktop.
Edit: What distribution are you using? Video acceleration does not appear to work on my desktop. While my CPU can handle it, I would prefer to look into why it is not working.