The first try of the match arrived three minutes after that when loose-head prop Gethin Jenkins blocked down an O Gara kick and hacked on for a score that Jones converted (10-3).
Ireland then produced the best move of the half. O Driscoll s deft inside pass released Denis Hickie and he combined with Geordan Murphy and Girvan Dempsey to bring play to within inches of the Welsh line.
Two more Jones penalties and one from O Gara saw the home side lead 16-6 at the interval.
The all important opening score of the second half came courtesy of another Jones penalty when O Gara was penalised for offside and the Irish out-half missed an opportunity to reduce the deficit when his 46th minute penalty went narrowly wide.
With the Irish being run ragged Jones added another penalty - a meagre return after a good phase of imaginative Welsh play - and O Gara was replaced by David Humphreys .
Ireland s only real backline threat came from Brian O Driscoll and when he darted through on the left the recycle was swept out right where Anthony Foley was denied by a last gasp Shane Williams tackle.
Then the clinching try came when Tom Shanklin took a marvellous line to tear the Irish defence apart and his perfectly timed pass allowed Kevin Morgan run untouched for the try. Jones knocked over the conversion and the game was gone way beyond Ireland s grasp.
With the outcome beyond doubt Eddie O Sullivan finally introduced fresh legs and Marcus Horan took a delightful line and a flat pass from Peter Stringer to score close to the posts. Humphreys landed the conversion and with Horan, Humphreys, Frank Sheehan, Donncha O Callaghan and Eric Miller injecting enthusiasm into the Irish side, they enjoyed their most profitable period.
A clever cross kick led to a try for Murphy but in the end the victory and the Grand Slam went to the side that most deserved it.