If you are new to DSLR photography, have a budget, and set on Nikon then I can recommend no better camera than a second hand Nikon D40, period.
The photos it takes are fantastic, and it's excruciatingly easy to use and you'll find yourself taking it everywhere with you.
The naysayers will say why use old technology? And it can't use any non AF-S lenses (which is onyl partly true - it'll accept the others, just wont auto-focus). But as a beginner you'll likely only want to use those anyway (ie. the kit lens that comes with it, which is very good on the Nikon side).
It's 6 megapixels, and has only 3 AF points and no bracketing. So sure, it's a limited feature set. But for someone starting out...it's a winner. A secondhand one should set you back probably about £130-£160 with a kit 18-55 lens, so as you develop your skills and find yourself yearning for more, you will have the money with which to invest in newer/more advanced kit in the future.
....and this coming from a Canon shooter! ;-) (Honestly, I'm always tempted to buy a D40, even though there is no logical reason for me to do so!!)