First off, congrats on deciding to put some money into a nice camera, it is definitely worth it. Here are a few tips.
1. Photographically, nikon and cannon will produce extremely similar shots. You should really have a hands on experience with both brands before making a purchase. Go for whatever feels best in your hands.
2. If your looking to take high quality video, go for a cannon, probably a t2i. If your thinking about this, make sure you are willing to learn about the camera, it is more complex than a Rebel Xsi, xti, nikon d40, etc.
3. If you want to take photography a bit more seriously and are willing to put time in effort into it, buy the camera a step above the one you think you need. You do not want to grow out your camera too quickly.
Good luck on your decesion, it can be a difficult one.