I'm sure your PC is much more powerful, however, the PS2's power is devoted to fewer tasks. Overall I would still imagine your PC much faster for games/graphics.
This is where the PC has an advantage over the consoles. They evolve quicker and can use the latest technologies. This may change with the new PS3 Cell processor which, for a geek like me, is a very exciting invention.
The PC is more powerful, but the PS2 is much more specialised, being designed purely for gaming. That said, your PC probably performs noticable better due to the half-decent graphics card.