I emigrated to Pennsylvania 8 years ago. You have a great opportunity ahead of you. I moved over on an intracompany L2 visa, after a couple of extensions and new classifications of visas the green cards finally came in after 5 years. My advice is... apply for your Green Card ASAP, so you can stay in the US on your visas while waiting for your permanent residency to process. Be prepared to return home on occasion to renew visas. A large company like Intel will have access to immigration lawyers to make the process easy, I highly recommend having a GOOD lawyer for this process. Oregon is known for being a very "Liberal" state, and the weather will be comparable to Ireland, oceanic.
Having grown up in Ireland, I didn't notice much of a culture shock, personally I think we're closer to America culturally than most of Europe. I find Americans extremely friendly, and very neighborly. Enjoy yourself, and congratulations on the opportunity.