Hi Aer Lingus,
My last flight on an A330 was from Zurich to London with Swissair; it is a wonderful aircraft - a truly nice experience. You will like Aer Lingus also and the crews are always very nice. I flew with them quite recently and I can tell you their inflight service is very good. The A330-300 is used on the nonstop to DUB, but the 332 is used to SNN (to allow it to fit in with the LAX flights, which originate in SNN and fly via DUB).
Personally, and I really don't want to get into a 777 -v- 330/340 argument (because I really do like the 777), I think the Airbus cross section is more comfortable as 2-4-2. The inflight entertainment on the 330s is very good (notwithstanding the lack of PTVs on Aer Lingus) and all in all, you should be well satisfied. PLEASE let us know when you come back, how you found it!