What is your price range for the receiver? Do you already have the plasma TV?
Here's my experience with DVI. I have none with HDMI, but I know a little about it. I have two DVD players and a HD cable box in my setup. One DVD player and the HD box are connected thru component video and the other DVD player is connect via DVI. I can honestly say that its hard to tell a difference in video quality.
The benefit of using HDMI or DVI is there is no signal conversion. It's just straight digital. For now, though the quality differences are minimal and I don't know how many receivers you'll find with DVI and/or HDMI interfaces. However, when the next generation of DVDs and players come out, there will most likely be a need for HDMI or DVI or both.
I wouldn't base my decision solely on whether or not your receiver has DVI/HDMI. Do your research. There are some excellent reviews here by both readers and administrators. Check them out. Then go listen to them at your local a/v store.