You will need a Win98 boot disk (and a 98SE CD including the Ser No) The boot disk you can create if you don't already have one by going to add/remove progs and clicking on the boot disk tab. Make the floppy first boot device Boot from it and at the prompt choose 'with CD-Rom support' option. at the next prompt type, format c: when it's done type the drive letter of your CD-ROM (which will be indicated before you format) So, assuming it's E: type E:setup and it should then start the process of loading w98. Don't forget to have all the drivers you need to hand also remember, if don't want to lose anything, to back it up before proceeding to format. Don't leave any peripherals connected before you start as it can confuse windows.