External Flashes Great Gadget Opinions Wanted: Extra Lens Or External Flash?

Opinions wanted: Extra lens or external flash? - external flashes great gadget

So, long story. I am very interested in photography and all aspects. This is my first digital SLR, and I would like some opinions. :)

I can afford a Nikon D40, and next to the camera kit, buy another. So my question:

If I buy a goal, you have to buy the 50mm f/1.8, or save a little more zoom (like the VR 55-200)? (Yes, I know that no 50mm AF with the D40, but I think it would be a great lens ...)

Or buy an external flash? I know that one day I buy ...

For more information: Shot of a variety of things, but soon I'll be shot many sports (football night, and indoor sports) and Occasional senior portraits (indoor and outdoor). This means not professionals, but like all the other photographers, I want to lead to surprising results, if possible ...

Therefore, suggestions? Please and thank you! :)