My current home machine uses 4 displays. My server uses 1 display. And I have a 6th display for my test bed. But for my main machine, I only use 4 displays at one time. One is a 37" 1080p HDTV. The other three displays are Acer 23" 1080p X233H's (identical). I use Windows 7 for the OS and to control the displays. The built in ability to place monitors above, next, etc, and extend the desktop works perfectly fine. I like having a central task bar on one screen and no where else. For controlling all my windows and the ability to dim inactive work, I use free software by SlimCode.com called SlimKEYS. It allows you to manipulate the windows via keyboard shortcuts. For example, I press Win+CTRL+M and it dims all windows except the active window. Very handy when watching a show or movie but not wanting to power down my other displays so I can still see my sites and feeds. It also has shortcuts which you can program to automatically resize windows to half the screen size, full screen, etc, and to place them on any of the displays automatically positioned to the left (half way), right (half way) or full screen. Extremely handy stuff. Check it out if you're into multi-display workstations.
This machine doubles as my HTPC and gaming machine along with workstation duties. I have my TV tuner feeding in HD content over air through my hauppage tuner to watch whatever is in HD that is free. I also of course watch my DVD's and things like Hulu and Youtube this way. Dimming the other windows aside from the video is really handy. When gaming I can game on my HDTV, or I can span it across my three LCD's if I choose (even more handy with eyefinity, or upcoming nVidia's option for this).
I operate wirelessly with a Logitech diNovo Edge for general use in my old trusty lazzeeboy recliner. Otherwise, when I'm wanting to game or go workstation on the thing, I switch to my Lycosa and weighted G5.
And a video of the dimming ability in action:
Very best, Edited by MalVeauX - 1/9/10 at 3:25am