NIKON all the way, I started with a Nikon F in 1969 (see photo), and have all the different generation Nikon bodies to date. Started shooting digital in 1992 with one of the first Kodak DCS 200 (Nikon body and lenses), and now shooting with the Nikon D3, and although I have purchase newer auto focus lenses, I still have and can use my 1969 lenses on my latest Nikon D3 body.
Point being, I suggest getting a camera system that will grow with you and allow you to keep up with technology. Also, as it has been mentioned, the camera & lenses are only make for half of the photography, the person driving the camera needs to know how to control the camera and technology.
Nikon RAW and Photoshop CS5, such an awesome duo!
If I was just starting out in the DSLR world today, I would invest in the new Nikon D7000, whichfeatures a 16.2 MP DX-format CMOS sensor, 6 fps continuous shooting and breathtaking Full 1080p HD Movies with full time autofocus. You will never regret, or look back.