2 Video cards-3 monitors as one huge screen

You need to set it up as an Eyefinity display, which involves DisplayPort monitors. Are you using DisplayPort monitors and that Eyefinity dongle thing that is apparently required?

I've curious about this.

you can't just use only DVI outputs on both cards? Similar to the way Nvidia surround works. The only reason for DP use is to enable more than 2 outputs through one card. So with two, shouldn't you be able to use DVIs only?

I can actually hook up 4 monitors thru dvi ports, not using display port adapters. I can get the 4 monitors to work but they are all are the same desktop. When I change one they all change. Looking to have one desktop across all 3 monitors. I have thought about eyefinity but cannot locate an active display port adapter anywhere . I probably wasted some cashe on the dual cards then.

You could Crossfire your 5870s.
For a single virtual gaming screen across 3 physical monitors you need an eyefinity setup where all 3 monitors are driven off the same video card.
http://sites.amd.com/us/underground/products/eyefinity/...

I finally got the active display port adapter, using cross fire when configuring them thru the cataylist softawre I can get thru to the point where it says arrange and nothing changes. I still have 3 duplicated desktops and cannot get all 3 to act as one. When I c;il on bezel the bezel screen does not show up, it just goes back to the screen. I have the higher resolutions available but when I cannot change to them. I have sent AMD a request but have not received any thing back from them. I have the latest 10.5 software with win7 professional.