first thing I do (I often buy these things as toys or for test animals so I don't brick a more expensive gadget) is download and install 'root checker'. you'd be surprised how many are actually rooted out of the box, and only need a SU binary or Superuser app to make it work. this allows root apps but since there is little to no developer support, forget custom ROMs or flashing an alternative recovery.
List of Pre-Rooted tablets as I know:
1. D2 Pads ($79 and up)
2. Emerson and Polaroids (same thing basically, around $65 and higher)
"If you treat your system like a kiln, don't be surprised when a brick comes out the other side."