Oxford earned a crucial three points in their bid to avoid relegation as first-half goals from James Henry and Ricardinho handed them a 2-0 victory over Southend.It was Karl Robinson's first win since taking over as U's boss.Henry fired them in front in the sixth minute with his ninth goal of the season, dribbling past two defenders and shooting low into the far corner from 16 yards with keeper Mark Oxley rooted to the spot.Ricardinho doubled the lead in first-half stoppage time when, after an 80-yard run, the Brazilian took a return pass from Jon Obika and saw his low shot deflect under the keeper and in.Oxford appealed that Ryan Ledson's header had crossed the line when it was pawed out by Oxley.Dru Yearwood shot just wide from the edge of the box for Southend and only a one-handed save by Simon Eastwood denied Anthony Wordsworth.The Shrimpers nearly pulled one back when Yearwood's fierce drive struck a post, before Eastwood saved Simon Cox's shot on the turn.