That's an unusual native resolution for a projector. Most projectors that I have worked with both in OS X and Windows have native resolutions of 800 x 600 or for the better models 1024 x 768. I guess I'm not up to date on the latest projectors.
In my experience 1400x1050 SXGA+ is currently a pretty common resolution for business/photographic projectors. The one in my workplace, a Canon SX80, is easily 4 or 5 years old, and the older projector it replaced used the same resolution.
It's certainly been a good few years since I've seen one stuck at 800x600, yet that's the maximum resolution Mac OS X offered (other than widescreen options).
Anyway, have you gone through the projector settings to see if you can change the resolution to something lower that you can use with your MacBook Pro?
I can use it at a lower resolution like 800x600, but the quality is poor compared with its native resolution. The image is quite fuzzy, and there's a lot of detail lost in images.
I'm not going to have a chance to play with the projector before I actually need to use it, so I think I'll have to use Powerpoint and Windows this time. It's a good thing I have access to those options rather than relying exclusively on Mac OS X.
I'll give SwitchResX a try when I have some spare time to mess around and make sure that its custom resolution works correctly and reliably. I've seen people report crashes and weird glitches when using SwitchResX, so I definitely want to test it properly before risking it when I need things to work smoothly.
Even if that ultimately does the job, I just find it strange that a new Macbook Pro would need a rather crude looking $20 3rd party utility (one that some people complain about when it comes to stability and reliability) to use a 5 year old projector that works fine with an even older Dell Latitude. Switching to a Mac has definitely been a mixed bag, with some neat things and clever design, but also quirks and limitations that cause headaches I really didn't expect.