Bad Format of 20G HDD with Win 98 SE

I have a system wi a 200 MHz Pentium MMX wi, 128MB RAM, and running Win 2K Pro. It would not run a Lexmark 73 USB printer. I decided that Win 2K Pro had too much overhead for system so did an Fdisk and Format on WD 20GB HDD using Win 98 SE boot disk. Win 98 only sees 8GB drive and will not see remaining 12GB of drive no matter what I try. Any help will be greatly appreciated.