The camera you are buying is a cropped sensor (or what some people refer as a crop body).
I believe I have the specifics correct... but someone else jump in and feel free to correct me if I miss a certain point below or it needs further clarification.
When digital sensors came out in SLR bodies, they were not as large as a true 35mm SLR film camera. For Canon, their sensor size on a cropped frame is 1.6 of a true 35mm camera and for Nikon the sensor is 1.5 of a true 35mm camera.
So if you put a 50mm lens on your new Canon, what you are seeing is NOT actually 50mm, but 80mm (for Nikon it is 75mm).
Now, technology has caught up, both lines have full frame sensors that you can buy. For Canon it starts at the 5D MII and upwards to the 1D MIII. For Nikon both the D700 and D3/D3X all have the full frame sensor. Meaning when you look through the view finder with a 50mm lens on the camera, you get a true 50mm focal length.
Most, if not all, consumer brand cameras have a cropped sensor - so it's not a bad thing. You, as a beginner, won't even notice and you probably wouldn't worry about it if I hadn't explained it!
The full frame sensor is nice for a lot of things... expanded ISO range (like mine can easily shoot at ISO 6400 without a massive influx of noise in my photos), plus, compositionally, it changes how you shoot a little more. But all in all, don't worry too much because it won't make that big of a difference in your photos.