For non-audio hardware, lots of mics, a big mixing board, and a good sounding room are critical. You will have to interface with studios that are both larger and smaller than you, so that means ADATs, DA-88s or both. Computer based systems are now powerful enough that full production can be done on them, but most people still track with ADATs, fly a few tracks over to the computer, tweak them, and fly them back to tape. Digital mixers are coming down in price to reachable levels. They are also great for surround mixing.
Dual monitors are a nice plus.
All of it. Apps, plug-ins, editors, the whole ball of wax. DVD Audio, or some kind of surround sound spec will be here soon, be ready. A few final notes. Often when recording, you will only be using one or maybe two mics at a time.