if you have a windows 98 cd, stick it in and boot from that. when it asks what you want to boot from, say cd. then when it asks what you want to boot, say command prompt with cd (not sure of exact wording)
then when the command prompt comes up, type "cd <cd drive>:\\win98" then hit enter
then type format c:
and then wait. it takes ages.
alternately, get yourself a copy of partition magic. install it in windows and run it from there. it will reboot the system and format however you like it automatically. and it formats much faster than msdos format.
have fun
