The defender signed for the south coast club after committing himself to a deal which is expected to run until 2009, according to reports this week.
O'Brien takes up fresh challenge
The defender signed for the south coast club after committing himself to a deal which is expected to run until 2009, according to reports this week.
During last January's transfer window, the 25-year-old wanted to stay at St James' Park and fight for his future.
O'Brien, who scored his first goal for the Republic of Ireland this year, was sent off during the recent 2-2 draw with Israel.