There is no difference between the platforms as far as the game is concerned. It is the same exact content. The only difference is where your Trophy/Achievements are tracked (Steam, Live or the PSN). The PC version can use community made mods.
As for your machine, you are fine and can run the game with fantastic performance.
Agreed, with the one exception of controller options. My good friend Mike at work has recently relegated Microsoft to /dev/null and is planning on getting the PS/3 version. He had played Fo3 on the PC for a long time, then tried it on the PS/3 and found that aiming is a little more difficult if your used to a mouse. Most importantly though are the lack of key-options, where the PC has a ton of buttons and can customize 12, 18, 24 or even more keys on the keyboard - which you can't do with a PS/3 controller.
He decided to get one of those keyboard converters for the PS/3 that allows him to plug a nice optical mouse and keyboard to the PS/3, and reported that it works great - with the exception that he can only map a limited number of keys and had more control options on the PC with being able to map more stuff. He still plans to play on the PS/3 and described how the game's controls are actually setup differently with the PS/3 vs. PC versions, but I found it interesting none the less.
I'm a modder, so PC-only, PC for life. For my friends on consoles however, I hope it plays smoothly.