By all means buy something - as the real issues of the digital world will show up for you in a natural "user experience" way. Computer photography is Adobe Photoshop, histograms, printer profiles, etc. Much less full frame sensor or not. BTW, Nikon has publically said that a full frame sensor is not real important to them.
I have a D200, a D2X and my lenses (must be CPU lenses to function totally with digital backs) work great on the digital cameras. A newer D2Xs is already out - a small upgrade over the D2X. I love my D200 a lot - and it is much smaller than my D2X - so I use it more now. (Still love my D2X in the studio in my office)
You will love digital. A totally new world, but much better in my mind. The final image, after you get great at raw capture, is amazing! Film's dynamic range (medium format) is what you are losing at first. The software can correct for this - but you will learn, with some experience, that there is lots to learn on the software side. It will be among the best time you invest in yourself.
Congrats in advance!