HeSaidJoe, If you're install the Win98 OS from a fresh HDD or a HDD that current Win95 (Not upgrade) then you're no need to format the HDD. 'coz Win98 did come with a Setup Boot Disk along with the CDROM.

What you need to do is juz boot your computer with that Setup boot disk will do. (Provider your computer have a CDROM and set it to boot from Drive A).