Where can a 19 year old rent a car in Northern Ireland?

I am a 19 year old student from the States and I need to rent a car in Northern Ireland, preferably for pick up from Belfast City Airport. If I could get insurance on it as well, that would be a perfect situation. Which companies can I rent from? A lot of them seem to have a minimum age of 21. Thanks!

Try contacting the Belfast Welcome Center or the Northern Ireland Tourist Office. They can help with car rentals and such. However, Belfast is known for its excellent public transportion. This seems to apply to much of the rest of Northern Ireland, too.
From what I've seen of various car rental sites online, 21 is the minimum age for all car rental companies in the UK and everywhere else.
Like roger k said, take the bus.

Here's a couple of links with lots of info. including car rental stuff. Use the Contact Us option to contact the people who run the site. http://www.gotobelfast.com .

Try http://www.arguscarhire.com . It has lots of companies listed at the bottom of the page. Maybe you'll have luck with one of them. Go to the FAQ at the top of the page and it has a series of questions. The one relating to age is what you want. First "I want to make a booking, but I have a question about age." Then click the questions you need from the next page and it tells you about an "Underage Supplement" that you can pay most car rental services if you don't meet the age requirements.
Best of Luck and Have Fun.

If you try the car hire company's in the airport and cant get a car there is a train station within 5Min's walk of the airport and also a very good city bus service the bus number you need is 3a and this will drop you at Belfast City hall right in the middle of the town if you are planing on traveling around Belfast go to the Belfast welcome centre in Donegal Place this is the street facing the front of the city hall its on the left hand side about 200 hundred yards down.