Dustin - again, this is why I suggest you RENT something before you buy - get a feel for what works for you. Conventional wisdom suggests that you want at least 400 ws per head for 4x5, because to get the same depth of field you'll need more power, as at any given f-stop, a larger format lens has shallower depth of field than a smaller format lens (due to focal length... a 150mm lens will have less depth of field than a 50mm lens will, at f8, for example). However, you may find that you like shooting wide open, and can get away with less power. Or you may find that you want to shoot stopped down all the way all the time, so you really need 1600 ws of power, not 200. Take an afternoon, drive down to San Francisco and go talk to the rental folks at Calumet, or boogie on down to Palo Alto and go pester the folks at Keeble & Shuchat for more info. They can arrange a hands-on demo with this stuff. Bear in mind that you're going to have to get a flash meter as well. You may want to start with hot lights and your 35mm, since they cost less, and you can learn well from them because they're truly WYSWIG. Then when you're ready to go to strobes, you'll have a much better idea of what you need in a light.