Just thought I would throw in my two cents here...
Everyone seems to agree that distilled water is ok to use, as it falls within the proper parameters for an aquarium. However, distilled water is not "perfect" water, and there is a lot of debate as to whether or not you really should use it.
I have been having this same debate with myself and my current tank, but honestly, do you really want to be purchasing distilled water forever, knowing its not the best water available for your precious ecosystem! I bit the bullet and bought me a 4-stage RO/DI unit from Bulk reef supply ($138 custom built). And it goes right under my sink, I get 100% clean water for my little pets, and for the freshest and safest ecosystem available! I also fill both of my other freshwater tanks with the water, drink the RO water for personal use, and can have water whenever I need it. Over the lifespan of an RO/DI unit, you will save a lot of dollars, a lot of hassles....and it is pretty cool trying to explain to your friends why you have this super cool water cleaner thing in your bathroom!
So in my less than professional opinion, go ahead and get an RO/DI unit...it will never hurt you, and you will officially jump start your aquarium hobby to full load knowing that you have the ability to grow any corals or fish that you may need and you have the cleanest water on the block!