Sorry. I should have mentioned this before. There are limitations as to what Eyefinity will do for you. This biggest limitation is that in order to use three outputs from the graphics card, one port MUST be the DisplayPort. If neither of your monitors nor your projected plasma TV has a DisplayPort input, you will also need to purchase an Active (as opposed to passive) DisplayPort to HDMI converter which generally run around $100.
Definitely do a lot more research before going out and making the purchase.