hmmm..
My answer to all of this is that DnD, as well as most role-playing games actually, can be played with only two people.. Highlander seems to be of interest. I think that Heroes would be fun with two people, or GURPS.. I guess that i'm just a strict DND fan though.. I've played DM for anywhere from 1-11 people at a time. With two players, a good idea is to each work on creating a campaign world and for the players to change shifts being DM/player.. I did that for about 6 months.. very fun and intellectually stimulating.
----YOU ROLL A 17, causing a volcano to erupt in both the Swiss Alps and the precambrian penninsula of ORDAK 9.---
EAT YOUR VEGETABLES!!!!!!!!!!! WOOOOOOOOOOOOOOO!