coderego,
While you do have a 4000's series card with an HDMI, realize that the HDMI out is only a version 1.2 I think. That means it won't support some of the high definition audio because it does not have a protected audio path. In fact, some of the cards wouldn't stream any audio through the HDMI I think, so you would have to use the audio from the motherboard or secondary audio card. I think the cards that had the audio pass through could only do 5.1. No TrueDTS or DolbyHD. But this really only pertains to movies.
Basically, I believe that the 6000 series cards were the first to have a protected audio path (by placing a audio card on the video card) and support 3D. I.e., it is a HDMI v1.4
It really comes down to what you need/want. If you don't mind not having some of the higher end audio formats for DVD's and blue-ray discs, than the 4000 series card will work (although there were some instances where I think the onkyo receivers uses as HDMI switches would not recognize ATI cards). You might take a trip over to avsforum and ask your question because it's kind of beyond just a JRiver thing.
Good luck,
Ed