There are several ways to setup multiple monitors with their own desktop.  These steps work after the second display in attached and turned on.

In Windows XP:

1. Right click on the desktop and go to Properties
2. Click on the Setting Tab
3. There will be a grey box with two blue boxes with numbers on them representing the attached monitors.  Click on the grayed out one and there will be two options that will un-gray out near the bottom of the window.  Select Extend my desktop to this monitor.
4. Click Apply.  You should get video on the other screen.
5. Click Identify and each monitor will have its' number on the screen.  Move the blue boxes to the same orientaion that the monitors are in by clicking and draging them.
6. Click Apply agian and then you can move the mouse and windows between the screens by moving them toward the screen you want the window to be on.

In Windows Vista:

1. Right click on the desktop and go to Personalize.
2. Click on Resolutions.
3. There will be a grey box with two blue boxes with numbers on them representing the attached monitors.  Click on the grayed out one and there will be two options that will un-gray out near the bottom of the window.  Select Extend my desktop to this monitor.
4. Click Apply.  You should get video on the other screen.
5. Click Identify and each monitor will have its' number on the screen.  Move the blue boxes to the same orientaion that the monitors are in by clicking and draging them.
6. Click Apply agian and then you can move the mouse and windows between the screens by moving them toward the screen you want the window to be on.

In Windows 7:

1. Right click on the desktop and go to Resolutions.
2. There will be a grey box with two white boxes with numbers on them representing the attached monitors.  Click on the grayed out one and there will be two options that will un-gray out near the bottom of the window.  Select Extend my desktop to this monitor.
3. Click Apply.  You should get video on the other screen.
4. Click Identify and each monitor will have its' number on the screen.  Move the blue boxes to the same orientation that the monitors are in by clicking and dragging them.
5. Click Apply again and then you can move the mouse and windows between the screens by moving them toward the screen you want the window to be on.

Another way to do this is is through the Nvidia Control Panel.

Manualy:

1. Right click on the desktop and select Nvidia Control Panel
2. Under Display select Set up multiple displays
3. Select Dualview (extend mode) for multiple desktops or NView Clone mode for the same picture on both monitors.  For clone mode the resolutions have to be set the same.
4. Select which monitor is to be the Primary Display.
5. Click Apply.
6. See the windows setup for adjusting the screen orientation.

With a setup wizard it will be under Display as well.  Just click the entry under Display and it will run.   Follow the on-screen instructions.  It may be neccessary to adjust the screen orientation.  To do this see the windows setup for adjustment.