|ive never played it (i play wow) but i did find a video that should give you the information you are looking for. its at youtube, he explains the low, mid, and high tier requirements and recommendations for running minecraft. |
i personally would look at building a computer instead of buying one off the shelf.
if you are unable to build, i guess i would have to say that HP is making some decent computers these days and for minecraft, im sure they have several that could run it just fine.