To answer the original question about what type of PC specs it takes to do the same as consoles?
The answer: An PC with an decently fast C2D (like and E8500), 2GB ram and an 8800 GTX will produce similar graphics/FPS as the consoles.
While the hardware described in the OP are quite low end when compared to today's "gaming" rigs. Its still much faster then system I mentioned above.
The thing is that most console games run @ 720p or less and most often 30FPS. This is a big deal as in order to go up to 1080p and 60FPS you need four times the rendering power.
Add to that that consoles run very low resolution textures and generally pretty low "settings" you should start to understand why it does not take that much to do better on PC now days.
Take a recent game like Bioshock infinite or withcer 2 for example and the settings on all low and the resolution to 720p. That's usually about what the console versions of said games look like. Even with your low end PC you are going to get way more then 30fps in thees games enableing you to bump up the graphics. Generally I would recommend staring with increasing the resolution to your native first (assuming 1080p) followed by texture quality. After that it becomes more of an mater of taste but the low, medium, high, presets tend to work pretty well.
Some people that are new to PC gaming do the mistake of setting the settings to high and then complaining about lag. You got to remember that games have variable loads. Some places are going to be more intensive then others so if you set your settings so that you get 30FPS looking at an wall of course its going to drop/lag when explosions and crap start flying around. You need to anticipate this. People who like to game with 60FPS set their settings so that they get 70-90FPS in low intensity situations.
Edit: I see now that this is a bit of an necro thread. Oh well