It seems like your gut is telling you not to do it, and I agree.

Run. Run far away from this guy.

Now for the rational explanation: What is he offering besides money? It's nice that he is willing to give you money, but does he have any contacts or experience or skills that might put you in a better position? Doing something just because you are cash strapped is a horrible idea.

There was a good convo here a while back for lawyers with software start up experience: http://news.ycombinator.com/comments?id=16419 pg uses WSPR in SF and Goodwin Procter in MA.