I've not watched Toure enough to decide whether he is much better than what we have. What i do know is that for all his potential Nedum isn't ready to get us in the top four. Maybe in a few years with some good defensive tuition.
Arsenal let in 12 or so goals less than us last season and Galas missed a chunk of the season so Toure must have been doing something right although they conceded 10 more than the other top 4 teams, and thats with two really good fullbacks in Cliche and sagna.
I would liked to have seen Carvalho come as he is a different class but Toure seems to have the right attributes lets hope he is a big improvement on what we have.
On MIcah - I personally don't think its worth throwing the towel in yet - he has a winning mentality is only young and definately has the presence, power and speed which just need some nurturing. I believe he got a bit big for his boots but with good players around him and the right attitude he could rise to the top again, it was only a year ago he was seen as the natural replacement to rag neville.