Advice on very small space for home voiceover rec. booth

Hi all, I want to finally set up a very basic home recording booth for my voiceover work. Since I'm not planning on doing any production, per-se, and am recording only single input voice tracks, I was wondering if it might be possible to create a very basic recording booth under the stairs in my basement. Yes, the space is small, but it's big enough for a mike stand, a chair and my computer monitor (I'm keeping the CPU outside of this space to reduce fan noise and make sure the thing doesn't overheat). The actual useable space is about 6ft x 4ft with a sloping ceiling (due to the stairs above). I'm not worried about noise of people coming down the stairs as I'm the only one that ever goes into the basement. In addition, since the space isn't next to any outside walls, it should theoretically be less prone to outside noise. I am planning on sheetrocking the whole space with fiberglass insulation and then adding acoustic foam on the interior walls and ceiling. Does this sound feasible for doing basic voiceover work? Will the sheer small size of the space be an issue for acoustics? I'm planning on using DigiDesign's MBox as my interface, so if any one has any input on the pros and cons of using this for basic VO work, please let me know... Any advice would be well appreciated... Thanks, Ian