In our family we have an X-Box,PS2,Gamecube,Dreamcast N-64 and two pc's.
If you want to do nothing other than play games then a console would be sufficient,but at the end of the day that is all it is ,a games console and perhaps a DVD player also.
The advantage of a pc is it's versatility in the different things it can do,but a pc purely for gaming is an expensive way of gaming although graphically a pc is better than any console(well the ones we have anyway).
Of all the consoles my choice of preference is the Gamecube( What's that I hear? Booo-hiss) because games published by Nintendo seem more playable than most others especially for the youger gamers.
Still think a good spec pc is the better option though.
That's one opinion for you.:0)