Please, he was indicted by the house, not convicted by it. The constitution reserves that right to the senate. People get indicted all the time and are later acquitted by a separate bodies.Again a perfect example of just how broken the US justice system is in favour of the powerful. Clinton gets charged in a political (not penal) forum, gets convicted, and then his conviction gets vetoed by a lower (as in less democratic) body.
You're right it was a political trial and not a criminal one.