I use a 400w ceramic metal halide w/ suplimented outside light. A 1000w would certainly be adequate as long as you have all the other important components in place.

good growin'...

How many square feet of tomato plants will you have?

Yeah, how many plants? 1000W would be ridiculous overkill for a couple of tomatoes, and totally inadequate for a large greenhouse full. If you do it right, 20W-40W of light per plant is enough. Do you have any natural light at all?

I start with two 250 mh on a light rail. the area is 3x10. I get about 27 plants, as they get bigger and in full bloom move too 2 400 watt argo sun, I moved them to grteenhouse when tomatoes were a little bigger than glof balls, if left inside I guess I could get about 13 plants,
gene

It depends what stage you want to grow them to. Plants started now will reach about 2½ feet tall (in a 1-gallon container) and require about 3 square feet each by the time they're ready to be planted outdoors in your zone. You could grow 4 of them to that size under a 400 watt light. (shrubs's estimate may be more for seedlings, up to 10-12 inches or so.) If you want to grow them exclusively indoors, you're best off with "patio" or other compact varieties, and then I wouldn't plan on more than one or two plants for a 400 watt bulb, with maybe a few basil plants on the periphery. But especially as summer heats up, tomatoes do much better outdoors (in a very sunny spot), where the more-moderate temperatures, humidity, breezes, and variety of insects help them to pollinate, strengthen them, and ward off pests. Even a compact variety, by the way, will do best in a large container: 5 gallon minimum at full size.