If this is a used drive there is most likely a jumper on the Header strip that needs removing to allow the drive to work in the USB Enclosure.
If it's a new drive you need to format it so you'll need to go into the Computer Manager then select Drive Management and scroll down till you find the blank drive and right click on and and chose [b]Format.[/b] If necessary you can break it up to as many partitions as you want and format them separately here as well.
If this is a used drive that you are attempting to recover data from you'll most likely need to take ownership of the files by following the directions here
http://tinyurl.com/3aw7
If you have encrypted the files you'll need to follow the directions here
http://tinyurl.com/orpmf
Finially if this is not connected to an XP computer you could have issues with the USB Drivers every 98 OS needs the USB drivers for the enclosure loaded so it can read the device that is connected.
If you want any more info click on the [b]Add Comment[/b] button and type in the question with the relevant information as to which OS and the other things that you are trying to do.
Col