You dont need 1000W to veg your plants. Your 250W bulb will do great.
As everybody else says, you are going to have serious cooling problems. I run a 600W in a closet and in the summer I need AC to control the temp. Yeah, like a lot of people I was greedy when I started. I wish I had gone for the 400W setup.
With the right setup and some experience, a 600W can produce over 1lb of dope every two or three months. How much do you need? Is it worth all the extra hassle of a 1000W bulb?