Its a great program, I've unzipped everything thats ever been thrown my way. Up to an including some weird-ass formats that I've never even heard of. (.uue, .yenc)
Now, if they're going to give you files on a ZIP disk (which were popular in the early 90's before the flash/jump drives of today), that's a whole 'nuther story, cuz you'll need a ZIP drive to read it.