Hi Hazelj,
Everyone's given great advice on this one.
I too am considering leaving my PhD and am concerned that leaving will affect my future prospects.
One of my mates left his PhD six months ago, and advised me that, if I am asked why I left the PhD, to state that it was for financial reasons that I was unable to continue study. I thought that was quite a good response as it meant you didn't have to expose yourself too much.