beckster - in case clubmans description doesn't make it clearer for you, you can think of it this way too :
There are two types of wireless network worth considering - one is the type that is strong enough to get from one side of Dublin to another and the other is the type that is only strong enough to get from one side of your house to the other.
The Irish Broadband offering is the type that goes across Dublin (from 3Rock, Liberty Hall, Ballymun, wherever) to your house. Once it gets to your house it has to end up somewhere and that somewhere is an arial . . . which has a wire coming out of it which is where the wireless ends and wired starts.
Now you can take that wire and plug it into a device which sends out a wireless signal strong enough to be picked up around your house and maybe down the road, but that's about it.
So, yes you need to buy a wireless router and a wireless network card. Actually your question doesn't talk about wireless network cards, so make sure you get a *wireless* one. Ethernet is the type you will need, but unless you go somewhere extremely bizarre you won't find anything other than Ethernet in a shop.
z