Your Windows Address Book is a *.wab file. It'll easily fit on a floppy.
From within OE you can can do "File>Export>Address Book" and get a *.txt file.
But it's easy to find the *.wab file(s) using the search function in Windows Explorer. Search for all files like *.wab. Choose the one you want and drag/drop to the floppy. There may be more than one if there are multiple users using OE.
On this Windows 2000 PC, my "Administrator.wab" is 700KB and is in C: \Documents and Settings\Administrator\Application Data\Microsoft\Address Book
It'll be in a different location on a Win 98SE platform.