Just gone in to check the specs of my epic gaming rig...
old style quad core 2.50 Ghz intel.
4gb DDR2 memory.
640GB 7200 HDD
and a Radeon 4830.
The graphics card I pulled from my old machine, I was too poor to shell out for a new one.
apart from that, the whole shebang set me back about £300, and don't listen to the crazy alienware fanatics who say you need to upgrade weekly, sacrificing half your paycheck to your local component store.
Now I happily admit, I think the latest game I'm running on PC is Just Cause 2, but it's flying at 1920x1080 with a bunch of settings up high, on a £300 machine with a 2 year old video card.
On another note, a friend of mine came into some cash and generously bought me a 360 and some games, so I could catch up to this generation, yet guiltily, I believe I've still spent more time on this web flash game, Gemcraft Labyrinth, than all the 360 content I have.
Lastly, please, whatever your opinions of WOW... How successful do you think it would have been if it had needed an i7 processor and a £300 video card. In many cases, being at the cutting edge of graphics technology can seriously limit your game's audience, just look at Crysis. (Oh no, that was piracy wasn't it? yeah, right...) Top tip, if only 200 PCs in the known universe can run your new game, don't cry when you don't sell a million.
To sum up, Blizzard and especially Valve (along with indie devs who can't afford an army of graphics coders), understand that there's a majority of PC gamers who for one, don't really care about technical specs, so long as it looks nice, and secondly, don't have the money to upgrade a PC, if it's that or skip your game, they'll be skipping it. WOW doesn't have 12 million Alienware owners paying them every month.