Need advise on Job Change

I got into a dilemma now.

A friend of mine had been urging me to joint venture with him to operate our own business in contracting firm. I really glad and happy that someone appreciated my ability and also has the opportunity to start up my own business and career with someone's help and support.

Here also where the problem lies. I just switched job into a consulting firm, where I am getting quite a good salary. Also I am having other commitment where I can't take the risk of without job or income for few months. If I get high salary in own company, this will put a heavy burden on the company too.

So what should I do now? Hope to get some advise from generous guys like you out there. Should I let slip this chance go by and stick to the consultant job, or take the risk and get similar salary in own company and fight for its survival in the market!