How do I avoid a dark subject when there's bright sunlight from windows?

Question

Possible Duplicate:
How do you avoid a dim portrait with a bright background and no external flash?

I recently shot some photos at a friend's wedding. The location was lovely with lots of light — sometimes too much. The sunlight from the windows and skylights seemed to overpower the shot and the subject/people were very dark. What are some ways to avoid this without using fancy equipment? (I'm just starting out, I'm not a wedding photographer or anything!)

Here is one example I took — and this is after I've lightened it somewhat with Picasa:

I'm using a Nikon D5000 with a standard 18-55mm lens.