I want to use a dual monitor setup.  I currently have a 19" flat screen samsung monitor with 1600x1200 max resolution (I think). It might be even less.  I want to buy a second monitor, a 24" samsung widescreen 245BW model.  I have a 8800 GTX video card; I know my monitor is not good enough for it.  My questions:
 
I want to use a dual monitor setup since I game and use autocad and want to start picture and video editing.  can I use two different monitors?  Can I turn on off if I only want to use one at a time (Like the 24" widescreen for gaming?)  Or would they act as one big monitor?  Is this easy to setup?

Assuming you are using Windows XP this is very easy to set up. Linux can be a pain. Right click on the desktop, click properties, click the settings tab, make sure the second monitor is selected, and then check the box that says "extend my Windows desktop onto this monitor". You can also play around with the resolution there.

Answers to your questions:

1) You can use different monitors for multiple monitor setup.
2) You can turn one monitor off when you only wish to use one.
3) For gaming, the game will display on one of the monitors (the primary). It is possible to spread the game across several however I do not recommend it if you are using the different monitors.

You shouldn't have any issues running the dual displays.  Set up the new monitor using the Display Settings (right click on the desktop, go to properties; depends on your operating system).  You can control which monitor is your primary monitor, what resolution each monitor is running at, etc.  They can be set up to act as one big monitor.
 
Clint

I have a similar question that was partially answered already.  I am building a new system with an 8800GT video card with dual DVI outs, E8400 processor, and 4GB ram.  I am going to be using a 22" for the primary and either a 19" or 17" for the secondary.  My question is will running this dual monitor setup decrease performance of the system.  The primary will be for gaming(EQ and WoW) and the secondary will be for desktop while gaming.  Secondly, would or could the second monitor be hooked up to the VGA output of the motherboard instead of the video card.  If possible, would this increase or help performance rather than have both on the video card?

I currently hae a 7900GT and a dual monitor system.. one 17" Viewsonic TFT, and one 15" Crt Philips, i had lying around.... To answer ur questions:
 
1) Depending on what u are playing, yes it will decrease performance IF you run both monoitors simultaneously, and game as well. Altho, seeing ur current config, i think it shud be negligible.  
 
The gpu has to render to two monitors simultaneously when using dual monitor configs. Hence the higher temps / loads. I often play cod4 with dual monitors on, but have to turn one off if there is a serious match. (to increas fps).  
 
2) Only if u use nvidia hybrid technology (8500gt / 8400gs) i think, u can use both both ur onboard vga and the gfx card. Other than that, both outputs shud be via ur gfx card.
 
3) I recommend two softwares for using with dual monitor setups, coz they are so cool. (A) Wallpaper master pro.. Only wallpaper changer that supports dual monitors (Diff wallpapers on diff monitors.. looks c00l )  
(B) Ultramon .. Gives you a second taskbar on the second monitor... makeing the os one a bit less cluttered.  
 
Also, Ultramon can be used to automatically switch off one monitor when a game loads , and other options aswell