Hi, I'm in South central Dublin too and I use Irish broadband. Been using it since September and have had no problems whatsoever. You call them, they come and check out your house for signal etc, which should be no trouble where you live, and then install it for you. We use it with a router and four laptops and it's been top speed all the time. No complaints at all. There's a few different packages but we're on the 49EUR/month one. Hope this helps. Their site is:
http://www.irishbroadband.ie/index.php