Non upgradability of a console is a bad thing to me, most games will perform based on the hardware and most good scalable games will look exactly the same or better than games did when you first put it together new games still play they just look about the same as games did when you bought it and a quick upgrade every now and again makes them better. My PC was very reasonable almost cheap the base unit came to less tha £700 and its played all the latest games and they look as good as when i got it. And unless you have a proper high def PC the graphics on any of the consoles arent even as good as what a new mid range PC can offer and on par with alot of older systems especially since no console has a full dx10 game yet.
You pay £50 a game 20 more than a PC game and PC games have free mods as well so the money you save on games alone saves you cash more than enough for an annual upgrade if you really want it consider you buy 10 games in a year thats 200 squid less than the cost of a new video card or doubling your ram. So your PC will constantly improve for a similar outlay in cash and im a notorious stinge. Nothing beats a good 4 player lan of flatout on the PC though or a 8 man game of farcry.