^ I'm tired of this DSLR = serious photography idea (alternatively, "if you're interested in photography, you must get a DSLR"). There
are other ways, they just don't seem to be that common on SSP. The old concept of "the best camera is the one you have with you" really applies. I've looked at books with professional photographers using point and shoots (along with DSLRs, etc.).
For something of better image quality, there is always the Fuji X system. X10 is $600, X100 (the instant favourite in the photography community) is $1200, and the X-Pro1 is $1700. Canadian prices, so should be less for Americans. X10 and X100 do not have interchangeable lenses, but have very fine lenses anyways.
There's also Ricoh's digital cameras, such as the Ricoh GRIV and GXR. The GXR is a very interesting system because there are no fixed specs. With each lens you purchase, you get an entire new back for the camera, similar to medium format cameras (without the price tag of one).
The Olympus Pen cameras are also exceptional and like the XPro-1 and GXR, do have interchangeable lenses. These guys were the pioneers of Micro 4/3rds in its modern iteration.
I've also heard nothing but good things about the Panasonic GF1 and Nikon 1 System. Canon is also coming out with a compact system camera, not sure if it is Micro 4/3rds.
Also, I know these are not what the OP is looking for, but just to show even more non DSLR, but still serious cameras do exist...
Leica M8 and M9 digital rangefinders, expensive as fuck, but still serious.
Hasselblad and Mamiya medium format SLRs. I'm not just meaning some old wedding photographer's 500c/m, there are digital sorts as well (which make the Leica seem like a bargain). These here are (along with Large Format, which do not have a digital equivalent, sorry) really the pinnacle of "serious, interested in photography" cameras. Not Canikons.
Anything film. 35mm SLRs, rangefinders, advanced point and shoots, TLRs, large format, medium format. This is what all the great architectural, street, and anything urban photographers of yesterday used.
By the way, I'm not picking on your post, bulliver, this is just a common perception I find, nothing specific to you.
That being said, DSLRs are a good choice, my post is just to prove that they aren't the
only choice out there. They do offer good image quality (although if you are used to point and shoots, it is common to find a drop in image quality at first which improves as you glide up the learning curve) and numerous lens choices. Canon and Nikon are the most popular and have exceptional lenses and accessories, but just to lay out all the cards, they aren't the only choice. Great stuff has also come out of Sony, Pentax, and Olympus's boardrooms.