I'm using a BFG GeForce 220 and an MSI GeForce 210 in two AMD machines running Helena x64 with no problems whatsoever.
Simply install the Nvidia drivers (I'm using 195.30) and you'll be up and running. I was using the built-in motherboard Nvidia 6100SE prior to
these cards, also without issue.
Nvidia and Helena love my 2 new Nvidia cards