Nikon and Canon are both good brands, a lot depends on how it feels in your hand and your bank account;) Nikon has always been more expensive when I have been buying. My first dslr was a Nikon D40x, although I was determined to buy a Canon 400D at the time, the Nikon felt better in my hand. I'm not knocking the camera or the images it produces, I have sold many photographs taken with it and while I still have the Nikon D40x, I wish I had gone with the Canon instead as the lenses on the Nikon D40x are limited to ones that have an AF motor inside (expensive lenses - so don't buy a Noink without the AF motor in the body!).
I upgraded to the Canon 50D several years ago and primarily use a 70-200mm 2.8 L for shooting equestrian sports, dog sports, wildlife, horses, landscapes and portraits on a professional basis. All the photographs on my website are shot with this Canon combo (with the occasional portrait using the 50mm 1.8 nifty fifty) http://southwestphotography.com.au
If you are considering a 60D and are serious about still photography, I would really suggest closely comparing the specs between the 50D and the 60D and getting a 50D if you can (and get another lens with the money you save on the body). IMO when buying a dslr, I do not want to pay for video components to the detriment of the still camera components. If video is an important feature - save your money and buy a high end point and shoot camera that has video capabilities. Or do what we did and buy a dedicated video camera as well as my dslr.
Some old lenses can be used on digital slr camera bodies, some need adaptor rings, most won't auto fucus so you have to do it manually.
There is a steep learning curve that comes with a dslr - not only the photography side, but in the processing. Unless you shoot entirely in dummy modes (in which case you will *not* get the best images that the camera is capable of anyway, so you might consider saving your money and buying a top end point and shoot that is likely to give you better images straight out of the camera), the very nature of digital images means that you have to learn how to process them just like photographers in the past did in darkrooms - the only difference is nowadays we use computer programs. While you can allow the cameras computer to sharpen/saturate/contrast etc, the quality of the image that you end up with will be far superior if you learn how to shoot RAW/NEF instead of jpg and process the images individually yourself (images also need to be differently processed according to the final output - eg a 16" x 20" will have very different sharpening required than what a 600px jpg destined for web display requires.
Only mentioned this last paragraph as many people are disappointed when they first get a dslr and get inferior photos to what they or a friend can get on a good point and shoot that does everything for you.