John,
here is a link from the Denon site that gives you an in depth compare of the 1804 and 2803. The main differences are :
1) The 2803 is 7 channel, 1804 is 6.
2) 2803 has "better" sound processing elctronics.
3) 2803 has more inputs
4) 2803 has better/more crossover flexibility
5) Main difference is that the 2803 is a pre/pro if you want to add a separate amp later.
tomtuttle drives his setup with an 1804 and is pleased with it. I have M60/VP100/Qs8 with an SVS sub and was driving all of it with an 1803 and that was more than adequate (just found an absolute steal on a 3803 and upgraded
). An 1804 ought to be perfect for you.
