If you are doing audio post - Foley, some sound FX and ADR/VO - you should get a passable audio interface. I personally prefer firewire interfaces.
MOTU (Mark Of The Unicorn) just came out with the Audio Express; I've had good experiences with MOTU gear over the years. The Focusrite Saffire series are okay. M-Audio interfaces are passable for USB devices, and since you already have Pro Tools it might be a no brainer. The M-Box Pro is probably out of your price range.
The AT4053b is a nice mic and can be used for multi-purposes, including production sound. If you do any ADR you should use the mic(s) you used on location.
When recording your own sound for audio post a "dead" isolated room is very important; otherwise you end up with strange artifacts and funky/mismatched ambient/reverb of your sounds.
BTW, a much, much better investment would be to hire me to do your audio post...