Which DVD player do you use to play non-anamorphic discs ? I have to say that I don't understand why you would need a separate player to do this.
Well, I didn't plan things that way, it's just the way it worked out.
I use 1080i HDMI from my HD DVD player and that automatically forces a 16:9 frame on my 4:3 HDTV (DVI-D input). Since the non-anamorphic image is actually in a 4:3 frame, that 4:3 gets dropped into the 16:9 frame, resulting in a rather small usable picture.
Now, if one's HDTV includes zoom controls so the 4:3 image can be appropriately expanded, then no problem -- however, mine doesn't (not needed with 4:3 FF or PS on a 16:9 HDTV). Another solution is to change the player output to 480p, however, my 1080i HDTV does a better job upscaling 480i than 480p, and my player can't output 480i via HDMI.
So, my solution is to use my Denon 2900 via component to deliver 480i direct to the HDTV.

(True, I could use component cables from the HD DVD player to the HDTV just for non-anamorphic discs, however, I need those outputs for my external scaler which drives my projector. In that situation, both anamorphic and non-anamorphic are fine since the scaler allows convenient adjustment between the two.)