Sure, this is also very useful to use for a HTPC also.
If you have the Nvidia control panel on your desktop (usually accessible when you right click or in the control panel), at display select change resolutions and then click on add resolution, this will let you create a resolution output (say 1920x817).
Also you should select adjust desktop size and position and on performance scaling select GPU scaling so it use the normal resolution of your display, especially important with zoom setting and even the shrink method (using display scaling will fill the screen output, which maybe useful with A-lens set ups without built in V-stretch scalers, make sure the projector can accept the new resolution first, otherwise still use GPU scaling and full screen mode).
I would try it out first using your computer monitor before hooking it up to the projector, especially if you don't use your PC for home theater. I'm saying this because I'd hate if you become frustrated with it, although resolutions not recognized will always restart after 30-60 seconds. Your settings should be the same with HDMI or DVI (take account to cable lengths however).
If your computer does not have an Nvidia control panel or only can use a VGA output, there is Powerstrip (which IMO is trial and error but almost as functional), although I don't believe it has GPU scaling for digital outputs.
I have a few pics done with games I played below.
Hope this helps!