Basically what it comes down to is technical knowledge. For people that are very good with computers, they can keep their computers virus free and maintained with very little effort. They can also upgrade their PC at a low cost. PC does everything a console does (graphics, modding, online play, control) better. In fact, PC users have been using mods and playing online a long time before console players have. That is why PC owners are generally unimpressed with XBOX360 and PS3. As for control, the keyboard and mouse offers more buttons and better precision than console controllers. Valve agrees with me; Half-Life 2 for the XBOX360 will do a great deal of auto-aiming for you, even on hard mode. If anything, you can always buy an XBOX 360 controller and use it on your PC for the few games that should be played with it (Assasin's creed comes to mind).
Basically what it comes down to is technical knowledge. If you don't know how to upgrade and maintain a PC, you are better off using a Xbox 360 or PS3. Keep in mind that a lot of gaming analysts say that consoles will soon become specialized gaming PC's in one or two generations. Notice that I don't include the Wii. The Wii has gone in a different direction than XBOX360 and PS3. That is probably why a lot of PC gamers own a Wii.
You could argue that PC's do cost more than consoles, but you do get more value out of it. With mine, I use internet, balance finances, play movies on my LCD TV, program, and of course, play games. The internet I use for a variety of tasks.
Console owners may be annoyed that I basically said that they do not have the technical knowledge to be PC gamers. I am convinced, however, that if they had the technical knowledge that they would be PC gamers.
