But speculation that Middlesbrough centre-back David Wheater is amongst O'Neill's leading targets is understood to be wide of the mark and Villa have made no bid for the 22-year-old.
The Aston Villa boss is believed to looking for a more experienced figure to fill the massive void left by Laursen, who was forced to retire with a knee injury at the end of last season.
And in any case Boro are reluctant to part company with Wheater despite their relegation from the Premier League.
O'Neill has always been renowned for favouring dominant central defenders such as Steve Walsh and Matt Elliott during his days in charge of Leicester.
And Curtis Davies, Zat Knight and Carlos Cuellar, his current crop of centre-backs, do not fall into that category.
Villa looked vulnerable at the back after Laursen was sidelined in January and in one spell conceded 25 goals in 10 games.
The likes of Upson (West Ham), Distin (Portsmouth), Brede Hangeland (Fulham), Philippe Senderos (Arsenal) and Vadim Demidov (Rosenborg) are being monitored.
O'Neill also has to find a replacement for Gareth Barry following his £12million move to Manchester City.
But in terms of prioritising, it is finding someone capable of filling Laursen's role that is taking centre stage for O'Neill.
He can call upon Steve Sidwell, Nigel Reo-Coker and Craig Gardner to play alongside the club's player of the year Stiliyan Petrov in the centre of the park.
Petrov is a leading candidate to take over from Laursen - and his predecessor Barry - as captain for the 2009-2010 campaign.
One likely signing for Villa will be Arsenal teenager Samir Carruthers, although he is very much a long term prospect and will initially be given the chance to play in the reserves.
Winger Carruthers was captain of the Gunners' under-16 side.
Villa's academy director Bryan Jones said: "He was offered a contract by Arsenal and turned it down. We were given permission by Arsenal to speak to him.
"We have agreed in principle a contract and hopefully he is going to sign for us on July 1."