I have a friend in Canada who is a landed immigrant. He is originally from Argentina. He used to live with me when he was an exchange student back in 2000.
He finished school is fluent in 4 languages ( english) Has a BA, is Teachers Assistant at Simon Fraser University. He left Canada to study in France, came back to Canada and got his masters. He is planning to become a Canadian citizen.
I was wondering if he can legally come to Utah to visit me? How can he do this? Does he need a visa?He doesn't think he can.

to visit USA, he would need to apply for a visitor's/tourist visa

Here's a similar question, with a great answer from Trailmix: http://www.visajourney.com/forums/index.php?showtopic=88849

A Canadian Landed Immigrant has to follow the visa policies of their country of citizenship. If their country f citizenship requires a visa to enter the US, then the Canadian landed immigrant alien will require a visa as well. But it should be easy to obtain.

Yes, from the department of state website:

Currently, Canadian citizens need proof of both their identity and citizenship in order to apply for entry into the U.S.

Permanent residents (aka landed immigrants) of Canada must have a nonimmigrant visa unless the permanent resident is a national of a country that participates in the Visa Waiver Program (VWP), meets the VWP requirements, and is seeking to enter the U.S. for 90 days or less under that program.

trav.state.gov