Steve Solomon , May 03, 2010; 09:02 a.m.
Congrats on your decision to go with either the D90 or 50D. Frankly, since yo uknow you are going FF in about a year, I think that your argument between which lens system is better, is really splitting hairs, for these reasons:
1. At this level, each system is of such high-quality at unless you print murals, and area "pixel-peeper", you will most likely not see a difference in image quality! People may argue this point, but I've done enough research into these systems over the years to realize that this is a fact. You'd have to make a MAJOR change to medium format before any image quality differences are apparent (especially at the standard print sizes). And for web design work (the lower resolution images typical on a website), this is even more true!
2. Each system has its strenghts and weaknesses (even with a lens "class" of focal length range), and each company is always coming out with new lenses, firmware, etc., so that you cannot make a blanket statement such as "Canon L glass is better than NIkon's Pro lenses", with conviction. Besides, both systems make superb FF camera bodies.
3. I've heard it stated that Canon's "per pixel" sharpness is higher than that of Nikon. However, I question even this statement, because I have seen image sharpness of equal quality between both systems. It's a matter of the skill of the photographer/printer, AND number 1 above.
I also think that if you travel, you might consider an m4/3 system (Panasonic or Olympus), because this "kit" will be MUCH lighter and more suitable for travel, plus, the image quality of this system does approach that of mid-range DSLRs such as the cameras you mention. Of course, for action or sports, nothing beats the DSLR.
Having said this, I truly think that the decision on which system to go with depends largely on ergonomics, ie., how the camera feels in your hand, operability, etc., rather than on pure "image quality". You need to take a media card to a store with both the D90 and 50D, and play with them, and compare image quality at home. I bet you won't find much difference, other than the ergonomics of each system! Just my 2 cents. Good luck!