Which is better for sports & portrait photography -- pentax k10d or nikon d40x?

I plan to buya dslr camera but its main uses will be for sports and portrait photography. From the reviews I've read, I like the image stabilization of pentax which is built into the system, unlike nikon where you have to purchase an expensive VR labelled lens for image stabilization. However, I also discovered that pentax mainly uses PRIME lenses which do not have a high zoom functionality. I need a high zoom range because when I watch badminton tournaments, I am so far from where the action is and I will be needing zoom lenses. I am debating over these 2 dslr cameras or a 3rd option can be panasonic dmc fz50 which is not dslr but has 12x zoom. Please help me! Sorry for the long question. Thanks in advance.