HDMI has the same digital video signals as DVI, it just uses a different connector and typically includes audio. Just get a PCI card with DVI out and get an inexpensive DVI to HDMI adapter.
Right. And you'll have to run a separate audio line because the hdmi won't be carrying it. You'll have to use a SPDIF or Optical out from your sound card if you want DD.
Be careful though. I had one DVI port overheat and burn out when connected this way (Nvidia 7600)