this is by far the best price I've managed to find the Nikon D90 for: £579 with free delivery! I'm personally a canon user, but that's just because I've spent a lot on lenses when I got my first canon 20D, however when I was working as a professional photographer I got asked by a lot of people "which is better Nikon or Canon?" to that I reply whichever you can get a good body and great lenses at the cheapest price. I haven't used the D90, but did like the D70 a lot, great camera! I can't see them going too far wrong with the D90, it has a great high ISO for shooting in the dark. check it out here:

Jacobs Digital | Nikon D90 Body

The D90 fuses technology from Nikon's flagship digital SLRs with an array of sophisticated functions to help you achieve superior results. Its 12.3 megapixel DX-format CMOS image sensor and EXPEED image processing system offer outstanding image quality across a wide ISO light sensitivity range. Live View mode lets you compose and shoot via the high-resolution 3-inch LCD monitor, and an advanced Scene Recognition System and autofocus performance help capture images with astounding accuracy. Movies can be shot in Motion JPEG format using the innovative D-Movie function. The cameras large image sensor ensures exceptional movie image quality and you can create dramatic effects by shooting with a wide range of interchangeable NIKKOR lenses, from wide-angle to macro to fisheye, or by adjusting the lens aperture and experimenting with depth-of-field. The D90 – designed to fuel your passion for photography.

a review of the Nikon D90 can be read here:
Nikon D90 Review: 1. Introduction: Digital Photography Review