Cheers cougar! Loving the support! The course I did is here http://www.digital-slr-guide.com/dslr-lessons.html
When I say stick it in manual, I did then go on to say "learn to take good pictures like that (or at least properly exposed sharp pictures with decent depth of focus) and all the other modes will then make sense." lets not get in the habit of posting partial quotes in the style of the daily mail.
The D90 has the normal Auto, shutter priority and aperture priority modes as well as a program mode. It also has several presets for portrait, landscape, macro, sports and night time. These give you a helping hand in a good variety of situations and should cover most peoples photography.
However, if you keep your camera in manual, even just for a week, by the end you'll have a much better understanding of your camera, its limits and how to overcome problems that automatic or priority modes can't. This allows you to preset for the situation, allowing for quicker adjustment to perfect photos. If you are trying to catch things that are happening rather than posed people/items then this is the key to having more good than bad photos!