Ric:
Your computer has that nVidia card, right? You should have loaded the drivers for it... If so, there may be a little icon in your task bar for nVidia Control or similar. Selecting that should give you a menu where you can change various things like orientation. (I think it is called NVRotate)
[Edit 1] Here is a link to the site describing the feature. Maybe they will have some help docs on how to access the software control if you don't see it in your task bar. BTW, I recommend the latest ForceWare drivers - v169.28. Here is the link for NVRotate:
http://www.nvidia.com/object/feature_nvrotate.html
Failing that, you should be able to right click on your desktop and get to the Display properties settings. Depending on which OS you have (WinXP or Vista) there are slightly different steps, but you should be able to navigate around and find the tabs for your GeForce card... might be under an [Advanced Settings] button (?) Anyway, under the tab for your card, you should see an nVidia control panel or at least an [Additional Properties] button... Poke around until you find the rotate command.
[Edit 2] Just in case you have difficulty, here is a link to a forum topic which has some screen shots, etc. It is relatively current, but if I remember your situation, your card is a newer generation than the one covered in this link, but it is similar enough that it should get you there...
http://www.nvnews.net/vbulletin/showthread.php?t=101188
Some monitors come with drivers which automatically trigger a rotate command, but I always found them to be flaky. Once you settle in on rotated or not notated, most people rarely switch back and forth, so I always used the task bar icon or right clicked to change. It is a bit disorienting, though, when the monitor is already rotated, so find the setting / command / button thing before you rotate the monitor, select it, THEN rotate the monitor.
Hope this helps!
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