a 250 is probably enough, in all honesty. but I guess that depends on how many plants you were planning on going with. If your goal was two, I'd move down to like a 150 or so, easier to deal with too. But for like 4 plants, yeah, that's about right.
I always find it rather ironic that individuals that are starting off growing mj are always the ones with the fewest available space, no offense Ragin. What really makes it ironic is those types of grows, in my opinion require the most skill. Most, if not all of your computer, micro, and very tiny grows are done by first timers, at least from what I've seen. Probably because our seasoned veterans (certainly not myself) view such small grows as too much of a pain in the ass, too difficult, and not nearly as rewarding. Of course I'm not talking about yours specifically Ragin, just generally speaking.
I always recomend to individuals to start big, then work your way down. It's alot easier than going the other way around. mj plants can get rather big if you arn't used to keeping them small, and it can create a headache. Think of it this way. Instead of viewing it as a plant to manipulate, view it as an elephant (bear with me here). If you were growing an elephant, you would want as much space as is available, it's a large animal. If you started off with a 10,000 square foot pen, if you notice that you have some left over room, on your next elephant, move down to a 5,000 square foot pen. Then continue moving down from there. Once you have had an elephant for a little while, then maybe try manipulating it to stay small. If I gave you a baby elephant, I'd probably guess you'd freak out once it started getting larger than the fishtank you had to keep it in, right? Same thing with your beloved mj. One step at a time.
I would recomend getting a 6-8' tall cabinet from home depo or something. start with that. If that works and you want to go smaller, shave it down to like a 5' grow or something, then move down from there. Starting small is alot harder, trust me.
Pardon my rambling, but I don't really think you were asking me all those questions, just giving my opinion. Take it or leave it. Either way I wish you luck. Once you finish your first grow, you'll be hooked. Cheers