He signed for £13.4 million in the summer of 2004 from Newcastle United.
"I'd been given an opportunity to play for the biggest club in the world and injuries ruined it. I played 14 games in two seasons. I loved it out there, though, as a life experience it was fantastic," he told the Telegraph.
"If I have one regret it was not going back after I'd spent a season on loan at Middlesbrough. I played virtually an entire season for the first time in ages. Boro had a bid accepted, but I didn't have to leave.
"I was 27, I was coming into my prime as a centre-back. I left too early. I was fit for the next two years and I should have shown them what I could really do."