It all depends on how the content is encoded.
Using two projectors. The left and right eye images are sent to different projectors which have been aligned to perfectly overlap and projected through polarised or tinted filters. The user wears the appropriate glasses and sees a 3d effect. With these you get perfect or near perfect colours. This is what you'll be seeing when you go to the cinema to see the latest block buster in 3D.
The separate left and right eye streams are encoded in the same image. This is how Google street view does its 3d. This will be the "classic" red/green filtering. You only need one projector, but you will need the old red/green glasses. The colours won't be perfect. This is what you'll be seeing when you rent/buy the latest blockbuster for your home DVD viewing.
As you only have one projector you need to go for option 2. So you need to find such encoded content. The only other hardware you'll need are the glasses.
As you can see from this screen shot of Google Maps 3D mode, I can see the separate red and green images (on the left) despite only having one "projector".
From the updated question you may have another means of getting the 3d effect at your disposal. This is where the left and right eye images are displayed alternately and you wear special "shutter" glasses which blank out the left and right eyes in sync with the images. For this you need an emitter which will be linked to the projector and in your field of view and the special glasses. A search for "DLP 3d glasses" will show you some shopping results and more information. This requires that the image can be displayed at at least 120Hz so each eye sees a 60Hz image to avoid flickering.
This is how the new breed of 3D televisions work.
Quad Buffer Graphics cards
Normally you have double buffered displays. The next frame is written to the back buffer which is then swapped with the front buffer so you get a smooth display. With four buffers you can display the separate left and right eye images "independently" as you have two front and two back buffers. This Wikipedia entry is basic but has links to more information.