Check out this great report from Gloin!

"Lurtz is played by New Zealand actor Lawrence Makaore, who played a Gang Leader in NZ film What Becomes of the Broken Hearted (sequel to Once Were Warriors).

Lurtz is the Leader of a band of Uruk-Hai at the battle of Amon Hen.   He personally killed Boromir in one of the most dramatic scenes in The Fellowship of the Ring.

Lawrence Makaore is a VERY big man (I can't remember exactly, maybe 6'4")  and has a very powerful voice which he used to command the Uruk-Hai.

I think Aragorn beheaded him later in the battle, I wasn't around for that part."

WOW! Talk about some great info.

UPDATE
Another ringer spy, Suomynona chimes with more information on this scene.

"He (Lurtz) shot about 4-5 arrows into Boromir, point blank.