Opinion on new Nikon Equipment?

In ten weeks time I'm looking to buy a new camera for my eighteenth, I was planning on getting the Nikon D5100 with its standard lens and get a 50mm lens on top of that with potentially the wide angle attachment.

I currently have a Nikon D40 with a 70 - 300mm Sigma lens.

When I turn eighteen I've been offered some nightclub photography and band promo shoots.

Does the new choice of equipment sound alright?

That's a very good camera and the 50 f1.4 is a great lens. You need lenses, not attachements. You may want to consider a 24 or 28mm next. What you want to get right away is a flash and I suggest a diffuser for it. Good stuff isn't cheap but if you buy good gear you won't regret it later.

Go for an 18-55mm lens or similar for your existing kit, rather than replacing a perfectly good camera. The 50mm will certainly be useful, though.

Screw-on adapters are rubbish, but a flashgun isn't a bad idea either.

For the D5100, 35mm is standard. 50mm is short telephoto. If you want wide angle, the cheapest is the kit lens. It goes down to 18mm which is as wide as you can go without too much distortion.

As it is, you already have a great camera. If there isn't anything wrong with your D40, you could opt for the 18-55mm, the 35mm f/1.8 (or 50mm f/1.8 if you insist) and an SB-700 Speedlight. All three should cost a little less than the D5100 with a kit lens and will give you the advantage of more light from the flash which is good for nightclubbing and a fast portrait lens.