[Wlug] USB Support in Linux 2.4.18

How can I tell if a specific USB device, in this case a removable USB hard drive, is supported by my kernel? I know that Linux 2.4.18 has "support" for USB devices. Does this mean all USB devices or just a few? I would think that the OS talks to the USB controller via a series of well documented commands and that its up to the controller to talk to the specific USB device. Does this make sense, or is there more to it? Thanks, Chuck