Welder: How is a Lincoln Weld Pak 100 HD?

A quality product. Be for-warned that its a 110v welder. That means a lot of people will want to borrow it. I would make sure it works and see if he turned in the warranty paperwork. You may be able to file as if you bought it new.
Make sure you get the regulator and the tank of gas. Without the tank and regulation this unit can get very costly very fast.