do not buy this (unless you need pro tools for as little cost as possible.)
there are a lot of interfaces out there right now. This is certainly not the best choice. In fact, with pro tools m-powered on the market now, there really is no reason to get such a mediocre piece of hardware.
you can get a 4CH interface that does 24-bit/96kHz. the mbox will only go to 48kHz. the output power is weak sauce too. its convenient to be buss powered, but get an interface with it's own power supply, you won't regret it. I noticed a HUGE difference in volume output. it didn't make sense to me at first, because the monitors have their own amps, but trust me, the output of the interface matters a great deal. you wont have to crank the output on your monitors and m-box to get a decently loud monitoring signal.
and 450 bucks?! really? do yourself a HUGE favor. save 50 bucks more and get an ECHO audiofire8 or Tascam US-1641. or spend $150 bucks less and get an audiofire4. you get 6 ins and 6 outs for 150 less, and up to 96kHz digital conversion.
There are a TON of products that are so much better than this. if you need protools, get something from m-audio. consider using an m-audio device for a while with some other software while you save up for pro tools m-powered.
and if you can do firewire there is absolutely no reason to go with an mbox 2, not even the firewire version. there are just too many good firewire interfaces out there. focusrite, motu, m-audio, apogee duet (if you're on osx), tapco, and lots more. sweet water doesn't carry a few of these brands, and the ones they do they only carry a couple of the models that the company sells.
I would say, if pro tools is not a concern, don't even think about this interface. If pro tools is a concern, think about a 610, solo, or fastrack from m-audio instead. you'll have to buy pro tools separate, but it's worth paying for hardware to be good hardware. with the LE system it's like paying for hardware to use software. what's the incentive to make good hardware under that paradigm?