Leo says it depends on his budget, but he'll need a big screen TV, and it's always a larger screen than you would think. If it's a media room, then a projector will likely be a better choice and he can go with as large of a screen as he wants. Projectors can range from $2,000 to $4,000 from Epson, to hundreds of thousands from Ronco. Then there's the screen itself.
He'll also want a Dolby Atmos compatible home theater system. Diego should check out AVSForum for more.