Stereophile had an excellent article on speaker placement that was written by Jonathan Scull in one his installments of fine tunes. I believe it was the October or August issue of 1998. I've probably gotten the date wrong (i'm at work) but you can probably find it on their web site. The article provided a very uniform way to set up speakers in rectangular rooms and I have found it to be unfailingly useful.
Speaker Placement
This is a tough topic for the newbies, and even some of us old guys. Regardless of the theory and even the software available, I suspect there is much that the more experienced among us could pass on with this problem. As you shift your speakers closer to the optimum position, what do you hear? What do you hear when the speakers are too close to the front wall, or when they are too far out? What do you hear when they are too close together and need to be moved further apart? What do you hear when they are too close to the side wall? What effect does toe-in have? What strategy do you employ to dial-in a new set of speakers or a new room? I am sure Albert Porter could help us all on this one. I will post some of my experiences if this topic gets rolling.