Irrespective of your background, you need to bring something good to the table when looking for a job. Maybe you're a wizard at server load balancing and optimizing database queries for example, which would be pretty valuable for an MMO development project. Or maybe you're really good at project management or user interface design.
Overall though, it's pretty amazing what backgrounds people come from in the game industry. If you want to see what I mean, go to http://valvesoftware.com/company/people.html and read the backgrounds some of the people at Valve have.
I'd personally start out by keeping the day job and making a few indie games on the side. It would be a great learning experience, plus it gives you a way to develop a portfolio. You might also look into modding a popular game like Half-Life 2. Being able to demonstrate a well made mod or game gives you credibility and shows you can do something. It's also getting you doing development that is essentially identical to that at a game company, minus the resources, larger team, etc.