Just in case you didnt already know:
If you are going to do a complete reformat, then I suggest this:
Make sure you have a good bootdisk, you will need it
www.bootdisk.com with the Windows 98 boot disk will be fine. The CD ROM drive will be loaded as the R: drive
Once you get the disk working, and you restart your computer, do the format, and then use the boot disk to install 98SE with R:\setup.exe
But thats only if you dont have a special System Restore CD