Air Travel: Aer Lingus, Continential and Delta offer daily services from Ireland to New York and from next month you can take advantage of the two for one specials, with prices from £379.
Driving: IF you are not driving, there are regular train services from New York. From Grand Central Station you take the metro North line up to Poughkeepsie. Taxis are available at each town en route. For trains that go up the west side of the Hudson take the M-Track from Penn Station.
Guides: A good guide for directions, accommodations and general history is The Hudson River Vallery by Tim Mulligan. A good novel that vividly recreates the history of the river is World's End (Penguin) by local author T. Coraghessan Boyle.