Wow...I'm a school teacher myself, and reading this forum I feel like I'm going to have to tell you all off. Petty squabbling on an internet forum really does make you look small time.
Back on track. I think if Vlaar and Dunne can get back to full fitness then the need for a CB will be reduced until the summer. We are desperate for somebody in midfield who can get stuck in and is not lightweight, overpaid and distinctly average at best (ala Delph, Bannan, Ireland).
I would personally (without sounding mad) go for someone like Shaun Derry on a short term contract. Will be soon ousted at QPR, no nonsense, gets stuck in, has experience of a relegation battle.
All of you who are thinking about top european players like Sissoko and Coutinho are not being realistic. We are about to be shunted out of the Premier League and we are not attractive to any top players. We need a bit of experience and a bit of fight. Aim for the likes of Coutinho in the summer after a bit of investment.