I'm sure it was configured for Perlico's service, but I doubt it would be hard configured. In saying that I mean it's likely that you can re-configure it to work with any DSL ISP.
When you say it doesn't work, do you mean that it won't connect to the internet or that it won't route the connections wired or wirelessly? I'm sure it's the former-most, but please be specific about the problem.
In the meantime, have a look at this:
DIGIWEB – Irish broadband internet & phone. Metro, Wireless, DSL & Satellite
Be sure you have your connection settings in the router set as specified in the above URL. Pay close attention to the DNS servers. Also, it might seem obvious, but make sure you have the correct username and password entered that you would have received from Digiweb.
Finally, I know you're from Shannon, right? As I'm from Shannon myself, I can vouch for Esat BT having a decent service in place. I'm using them now for just over a year, and I'm as satisfied as I'm going to be where ADSL in Ireland is concerned, regardless of the ISP. Esat BT offer the best prices around. They have not yet been beaten. All you have to do is pay your line rental with them and take their phone service (which is fine, and cheaper than Eircom's). With that, for the top broadband package of 3mbps, you'll pay only €50 a month which includes your line rental (usually about €25 a month).
See:
http://www.esat.ie/echannel/BTres.po...Label=homePage
Seriously, take a peek and you may be in for saving cash.
Oh, and no I don't work for BT and I'm not a salesman.
G'luck,
Seifer.