Sounds like you installed a FAT16 formatted partition, which is limited to
2GB.  As I recall, FDISK under Win98 *asks* if you want support for large
HDs before partitioning, and if you answer Yes, it creates a FAT32
compatible partition instead (which will give you the full 20GB).

If this is the case, you can either start over and run FDISK correctly
(which will delete your current Win98 installation), or download BootIt NG
( http://www.bootitng.com ) and convert the FAT16 partition to FAT32
(probably simpler).  Simply unzip, execute bootitng.exe to create floppy,
boot the floppy, and when the Welcome screen appears, select Cancel (to
abort the install).  Follow the prompts to the main menu, and select
Partition Work.  Now select the FAT16 partition, hit Resize, select the
maxsize (should be set by default), select FAT32, and hit Ok.  When
complete, hit Close to exit Partition Work, remove the floppy, and reboot.
When rebooted, Win98 will be running as FAT32, the full 20GB capacity.

HTH

Jim