In reply to Oujmik:
Racesport isn't as durable in terms of the sidewalls, and I think* depth of compound as the primary focus is on low weight), having said that, you really should go for a model with the Black Chilli compound - this stuff is amazing, it even gives good grip riding wet roots. The difference between the standard Mountain King 2s and the blacjk chilli version is astonishing and well worth the extra££££s. They also last well (I've done 1500 hard miles on my rubber queens, and I think they'll probably go another winter season (I've just switched to brand new X Kings ready for my trip to the alps in a few weeks)
I would suggest dumping the idea of the trailkings unless you are riding in Muddy conditions (which hopefully you won't for a while now) and go for the X King I suppose it depends on whether you want an all round tyre or one for the season. (As an all rounder, the rubber queens are hard to beat - a bit draggy, but loads of grip and shed mud well)
also look at some of the german websites like
http://www.bike-discount.de/en?currency=3&delivery_country=190
http://www.rosebikes.co.uk/
which tend to be 10-20% cheaper than uk on-line shops especially for conti tyres.
As others have said, 2.2 on the rear is plenty. I currently run rubber queens 2.4 front, 2.2 rear for winter conditions and X kings 2.4 front 2.2 rear for summer. I am doing mainly All mountain and alpine downhill riding at the moment (on an xc bike), and would probably go a bit thinner and lighter if I was just doing XC stuff a bit more