I'm put off by PC gaming, but not for the same reasons it seems. The cost of the system, while somewhat prohibitive isn't where my problem lies. Actually, it isn't even one single problem it's an entire list!
1) Fewer games are being produced for PC these days. Often, when a game is released on the PC, it is also released on the consoles. Of more than a dozen friends who regularly play games, only two of us actually keep our PC's up to date enough to play PC games, meaning I'm generally forced to play the game on a console if I want to play with my friends. I place greater value on playing with people I know than I do on a control set that I often prefer and toying with the dark powers of technological wizardry.
2) Even when things go well with a PC game (i.e. my system can handle the game), I am often forced to invoke the powers of demons in order to divine the magical combination of settings required to overcome the myriad technical glitches. With a console game I just pop the game into the drive and I'm off. As my free time becomes ever more valuable, this is becoming all the more important.
3) Finding a place to purchase PC games is becoming increasingly difficult. There was a time when any game retailer would have a good selection of PC games. These days, walking into the PC section of most game stores is like taking a trip back in time a half decade or more. I can find copies of the Diablo Battlechest but god forbid I can find a copy of Crysis. Digital distribution is an option, as is online purchases but since my time is fairly scarce these days I don't like spending a few days waiting for my game to arrive by mail or finish being delivered bit by bit via the internet.
4) With the exception of one person, everyone I know is forced to play console games due to the cost issue. Most people in my peer group don't have a large amount of disposable income, which means they won't have up-to-date hardware and they often are forced to purchase games on the used market. Since I value playing with people I know, many of my game and platform choices are made by others. My friends purchased L4D for the 360. In spite of the fact that I could play it on PC, I followed in their footsteps in order to play the game with them. This means that the only time I'm the one picking the platform is for games that no one in peer group is interested in, and generally these are things like RPG's and RTS games.