becausae you are using Windows98 and Windows98 only support FAT or FAT32. You have to partition your HDD to 32GB (max, 32768MB) for each partition. After partition, you MUST format all the partitions in DOS mode. After formatting, reboot your computer...... You can partition it into one 80GB in FAT32 but (if) you store a lot of small files into your new HDD. You can get the message about "Your HDD is FULL" even your still have 50GB space