Congrats MrBig.  In 2004 me and four others quit our jobs (where I had worked for 16 years) and started a company.  We got sued by our former employer, I blew through my entire 401k and then some, my income was zero for 14 months, and we ran out of money before we could make a sale.  
On the other hand, I was my own boss, we came up with a workable product in just four months (just couldn't get a foot in the door to sell it), and it was the best experience I've ever had.  I'm glad I did it and would do it again (if I had the money).  Taking the risk is worth it.