I have found FastStone Image viewer to be helpful for our camera club projections/competitions. Set the video to dual display with the laptop as display 1 and the DLP projector as display 2. Display 2 is set as an extension to the laptop screen (not a clone).
FastStone allows you to highlight thumbnails on the laptop screen while showing the full-screen image of the thumbnail on the DLP. This makes it very convenient to show each image, and then delete images (and even rearrange the order) during the competition as images are accepted or eliminated.
The dual monitor capability is on the latest version (version 2.7) only. The program is free to try for about 20-30 days before registration and payment is required. The cost is modest. You can find information on it by conducting a google search ("faststone").
Anyway, this seems to work for our club - and I have tried several programs (Irfanview, windows picture and fax viewer, powerpoint, and lots of others that just didnt fit our needs). But I have not tried photomagic, lightroom, or aperture.
By the way, we require our camera club members to submit images as jpgs with sRGB and 1024x768. I havent seen a problem yet with presenting color inaccurately (other than from the limitations of the projector itself).