JJ, I think John is mentioning that you could use 3 identical speakers so they are matched perfectly. It is important that the left/right speakers have the same drivers and are tonely matched to the center. That is why it is not a good idea to use differant brand speakers in a HT setup. If you go with the Center W150, you would be fine as Axiom uses the same drivers.
It is important to try to get the tweeters of your left/right speakers as close as possible on the same horizontal line as the center. You also want them to be at ear level or close if possible. Below is a pic of my setup, you can see the center is mounted on the wall below the screen, close to my m60 tweeters. I have it angling up slightly, so the people in the back row also get a good experience.
