Not to say that Pentax and the others can't take good pics. They can take just as good of pics as the Canon Digital Rebel. But if you are looking to ever take pics as more than a hobby, you will need to be in the Nikon and Canon world. The lens, accessory, and pro options for the other brands just aren't there.
My friend, stop right there. You clearly have no idea what you are talking about. Its OK to say you prefer Canon over other brands, but do not sit there and type and say they are clearly the best over all. I prefer Pentax because of function, and I have older pentax lenses from my K1000, and also I find the Pentax image quality to be great. I don't care if you are a pro or not (judging by your comments, you don't sound like a pro), but just because you prefer one, doesn't make it the best on the market. I also prefer Nikon over Canon for ease of use, and their interface, as well as other features.
So quit being so ignorant just because you are a Canon fan-boy