Microsoft Office 2008

Looking to buy Microsoft Office 2008, but the problem is that here in Canada it's going to cost about $179. But if i take a 20 minute across the border to Michigan, I can get the very same software for $129. I'm just curious if there will be any restrictions on the software that will prevent it from being used in here in Canada since I purchased it in America. Will the product key still work? Is there any other reasons I shouldn't?

Thanks