Would agree I have all three of my rigs in Eyefinity/Surround setups. While it does cost quite abit to get it up and running I could not go back to a single monitor after having my Eyfinity setup for over two years now.
Personally I think a Crossfire/SLI setup is a must for gaming there is just a lot of pixels to push to a 3x monitor setup even with three 1080p monitors you are talking about a resolution of 5760x1080. Get two of the best GPU's your budget can manage and you should be OK as long as those two cards of good quality and your PSU can handle the Crossfire/SLI setup that is.