Well boys, after a little bit of searching while wondering the same thing myself, I think I may have found the definitive answer to this question...
Key Poulan, whom is a descendant of the Poulan's that started the company, has explained it here in his blog I've linked:
Google
He's a musician, it seems, and has no part in the chainsaw industry whatsoever. However, reading the linked blog (especially the lower half) will explain the origination of the surname, its pronunciation, as well as some other history. They weren't French, the surname actually being "Poland." However, there was a spelling error on their "immigration papers" which actually date back to the 1600's, according to him, and thus "Poulan" was born.
He has actually made a youtube clip with how his name should be pronounced:
[video=youtube;XY37cuvbY8s]http://www.youtube.com/watch?v=XY37cuvbY8s&feature=share&list=UUuGvw4oJxQb90iiiDv3OtAg[/video]