Guys its not that stupid a question.
PC's have the best graphics processing power. Their max graphics are 99% of the time limited by the game engine and not the hardware, whereas the opposite is generally true on consoles. However, with the stunning levels of optimisation for the consoles, games on the PS3 (and sometimes Xbox) look better than other games on the PC, Gran Turismo 5, for example, began to be released when there was no decent looking racing game or simulator on the PC, and to my eye is the second best looking game out right now, after Crysis Warhead.
The level of hardware advancements in PC's right now has put them back ahead of consoles despite the limited optimisation possible with such a varying platform, but to say graphics on PC's are always better than on the consoles is not true, for example games like MW2 look exactly the same on all consoles and platforms, the only potential difference on PC being support for higher resolutions and 3d displays.
PC's have more graphics power, however consoles use their power much more efficiently than PC's, and so can outperform PC's which are specced several hundred's of pounds higher than them in raw hardware with good optimisation.