a flash drive is any such drive that has flash memory to let you store things on it.
also called "usb key", "pen drive", "memory stick" and probably other things. basically its just a little tool that lets you store your files on it. they use usb2 (also compatible with the older usb1.1), which most computers have now. windows2000 or XP or mac OSX will load the things straight away with no more messing. windows98SE will require you install some drivers to get it working.
example of where to get them from:
http://www.ebuyer.com/customer/products/index.html?rb=94 32857461&action=c2hvd3N1YmNhdGVnb3J5X3BhZ2U=&sub cat_uid=405
so instead of using a floppy disk just to transfer some files from machine to machine, use one of these. they also store _far_ more than a floppy. and some are very cheap, for their capacity.