Have a Game Cube at the moment, but fancy trying Modern Warfare. What do people recommend for buying second hand. Any help appreciated as I really have not got a clue!

Xbox if just fir gaming, ps3 if you want to use it to watch hidef movies too.

not sure if Microsoft have sorted the issues out with x-boxes yet? I had one for two days and then it broke! I sent it straight back for a refund and purchased a ps3, never looked back.
The ps3 is superior in my eyes.

PC is the best for 1st person shooters IMHO.

But how much does a PC with enough processing power/graphics card/sound card cost ?

Probably not that much these days – a few hundred? The machine I use for games was bought from Aldi of all places a year or two back and wasn't expensive. Quad core processor and a GeForce 9500 – ok it'd struggle at the top graphic levels but at mid levels it still looks much more impressive than the same game on my sons X-Box 360.

His £400 laptop plays the game fine as well.

xbox for gameplay/online. ps3 if you fancy a blue ray player

I could have sworn I had already said that 😉

PS3.
Blu-Ray built in and you don't have to pay extra to play online.

We have both Xbox360 and PS3. I bought the PS3 version. Prefer the controler, free online play, doesn't have more cooling fans than drax powerstation (ok my xbox is 3 years old).