If you buy a lot of games and buy them to keep, a gaming PC of equivalent performance can be a LOT cheaper.
When Circuit City was still around I was getting the same new releases consoles would get for 50% of the price or even lower. Orange Box was $35 at launch ($60 on consoles) and only $15 days later on Black Friday. I got Call of Duty 4: Modern Warfare for $16 less than a week after launch. Shadowrun was less than $10 while it was still $60 on 360 (1st game with Windows vs. 360 online play). Even with the current consoles, buying only exclusives on the consoles and all multiplatform ports on PC has more than paid off my PC hardware.
Hope you had fun paying $60 for inferior versions of Batman Arkham [X], Grand Theft Auto IV, Crysis, Bioshock, Mass Effect, Gears of War, etc this past generation.
Let's not forget that the vast majority of console households have a monitor, mouse, and keyboard.