If you would use it as a PC, it would be very low end one. Consoles are meant to be used as consoles.
the ps3 is one of the most powerful computers on earth. it wouldn't be "low end"
it would suck because it is only the processing cells that are good.
the video sucks, the memory sucks, the HD sucks.
and you cant just hook a ps3 CPU cell into a PC, it just dont work like that. nor can you put PC hardware into a ps3.
the fact that you have seen things installed on ps3s is because its been hacked recently.
but short of playing burnt ps3 games on it, its not that useful