This is the closest that I could find. http://www.hardocp.com/article/2010/04/12/ati_radeon_hd_5870_eyefinity_6_performance_review/4
For Battlefield:BC2 a single 5870 at 5760x1200 isn't that good. Effects and HBAO weren't highest or on, nor was AA possible. These are some big screens however, if you use three 1680x1050 screens things should be a bit better. Notice also that the 5870CF setup was better. There effects were set at high, and you gained 4AA. One last thing to keep in mind is that this is a newer game, and older game like MW2 should run better/faster. Assuming your going for 1680x1050 panels I'd start with one 5870. But don't be surprised if you need another to max things out.