If you do go with a 3 monitor setup make sure you get one/all 3 that has a DisplayPort input, if not then it will cost you another $100 for an active DisplayPort-to-HDMI converter.
Another thing that you need to think about is currently as of the 9.12? drivers only about 24ish games can handle Eyefinity while Crossfire is enabled. Depending on whether you play those games or if you are willing to wait a month or two for support for other games is up to you.
I don't plan on buying for a while (until Jan 2010), and the driver support is something I can live with. I have seen a bunch of 3rd party applications that fix the issue, and for the games that arn't supported, a single 28" monitor will suffice. I expect driver support to get better within the next year - I hope. I also don't mind buying the Displayport converter. I am merely wondering if the peripheral vision gain is worth it. I have $3000 to spend, so I feel like it silly to only go with a single monitor display. The productivity aspect isn't an issue because I mainly game. The work I do is simply writing papers, so screen real estate isn't a big factor.
I would defiantly go with the 3x1 eyefinity setup. After doing a lot of research and reading reviews I am defiantly going to go with this setup in Q1/2010. This forum doesnt have a lot of information on it but I have been reading Hardocp.com and they do many extensive reviews on it. You might want to check it out if you havent already.