There's one thing that really makes all the difference for me between PC and console gaming (Seeing as thats going to be the hot topic on this post)....anti-aliasing.
You console-only guys have no idea how bad you have it. When I am playing on my 360 it looks like some sort of 8-bit creature has puked all over my screen. When I play on my PC I can play HUGE maps and see every crisp line on the horizon, thus making it easier to identify friend from foe, etc, etc. and it doesnt give me a headache when walking through a 'grimey' city...god on a console you can hardly tell the wall from the floor.
Whether this (plus: Much richer GFX, faster load times, an insane frame rate, a delicate, accurate, and modular control system, games that could handle 64x64 player maps years ago, the ability to CHANGE the power and/or components of your system at will, the ability to adjust ingame controls and performance to meet your own requirements, infinite upgrade capabilities and instant accessibility, no fees to game online, downloadable software that can be stored server-side indefinitely (e.g. Steam), the ease (and it is easy when you have google)of fixing your PC when something goes wrong instead of praying the warranty is covering your red ring, thousands of mods and the ability to create your own, a back catalogue that dwarfs ALL consoles, a near-infinite wealth of other non-gaming capabilities, and the knowledge that every console will eventually die and PC will live on) is enough to warrant the extra money that is yours and only yours to control and do with as you please, is obviously up to you.
I personally feel I get my extra few hundred pounds worth out of my awesome rig which has a much grander purpose and lifespan than any single-purpose console. Plus I love getting my hands dirty and building/adding/changing bits in my PC, its a hobby alongside my other hobby: gaming.
Each to their own, but don't come wailing about how cheap and 'nearly the same' consoles are to PC gaming when really the are incomparable platforms.