found a couple of CDs but not sites yet with lyrics/tunes.
In the search by artist section, type in "Dervish" and check out the listing for the album "At The End of The Day". If you have RealAudio you can hear the clip of Ar Éirinn ní neosfainn cé hí.
I also found listings for it at this website: Click here
As far as the other, Erin Gra Mo Chroi, I found references to a CD called "At the Racket" and a recording by the Boys of the Lough called The Fair Hills of Ireland (apparently not on CD?)... still would be looking but I really should get back to work...