This is a common concern (and one reason that I wrote my
HDMI FAQ recently). As E'pin points out, the audio from an HD-DVD or Blu-ray player can be connected to almost any existing surround receiver or processor using multichannel analog cables. That has been done to afford backward compatibility with the huge base of installed receivers and processors that lack HDMI 1.1 or higher inputs. A number of HD-DVD owners have also been using their players' SPDIF (coaxial or optical) outputs with great success: the HD-A1 and HD-AX1 both convert Dolby Digital Plus to full bitrate DTS on the fly.
If you happen to have two DVI or HDMI sources, you can use DVI-DVI and DVI-HDMI cables (such as
these two ) to connect both sources to the 970 and the 970 to your display - the 970's switching will pass HDMI video without any trouble. If you only have the one HDMI source, you may find that running the HDMI cable straight to the display for video is just as easy.