I was driving from Brittas Bay to Dun Laoghaire for couple of years.
It takes about 45 min during kids holidays and could take 1.5 hours if your work is 9-17.....
when Wicklow by-pass will be finished( supposed to be 2010, looks like this delayed), you'll save another 10-15 minutes - there is alwais traffic jam during the summer, fridays are the worst....
Also been driving Brittas Bay-Tallagh , the same time, if you DO NOT work 9-17.00... otherwise you'll stock in Kilmacanogue area....
longer driving time during the winter.....absolutely lovely arey, but check water supply ( very hard water) and electricity - we lived there 6 years and had electlricity interraptions during busier summer months .... also look for house further away from Central Parking- could be overcrowded on summer....