im not sure which are carriers but the networks we have are 3, O2, Vodafone and Meteor.
yea id probably go for something on a contract if i was to get one.
It seems Vodafone Ireland have the Samsung Galaxy S.
Samsung i9000 Galaxy S - Pay Monthly - Vodafone Ireland
They also have the Sony Ericsson Xperia X10, another decent phone although it hasn't yet been upgraded to the latest version of Android, although it apparently will be soon.
Meteor have the Galaxy S, HTC Hero, Xperia X10, HTC Legend, HTC Desire and a few others:
HTC Desire on Meteor -
https://phones.meteor.ie/phones/htc_desire/#what-you-get-tab
O2 Ireland also have the Desire and the X10.
3 have the Galaxy S and some lower-end Android models.
If I were you I would be looking at the HTC Desire or the Galaxy S right now.
Spec-wise there's not a massive difference between the two, but the Galaxy S has a slightly bigger screen and an additional front-facing camera for video calls. So you'd probably have to pay a little bit more for it. The Desire is a seriously good phone too, my cousin has one and it's fast as hell.
You should try going to a few stores and seeing if you can demo the two devices and what kind of deal you should get. But don't buy from a store, buy over the phone because if you get either of those phones, then you can bullshit the person saying that a rival network is offering you a better deal.