Hi dont worry about formatting a floppy just go to the control panel and then to add\remove programs then go to the create bootdisk tab and create a bootdisk then restart your computer go in to the bios and find were it says floppy seek and then enable it then change the order that the computer boots from, so it should start IDE-0, then CD-Rom, then floppy, you change it so the floppy boots first then CD-Rom save the changes and reboot with the boot disk in the floppy drive then wait awhile for the computer to start reading the floppy drive select start computer with CD-Rom support make sure your windows cd is in the CD-Rom drive.
After the computer has finished readind the floppy you should be in MS-Dos withe the command prompt C:\ type in A:\ then type format c:\ that should format the drive you see you cannot format or erase something as big as windows unless your in DOS after the hard drive is formated type D:\ which should be your CD-Rom drive letter or if you have got 2 hard drives it might be E:\ then go to setup and install a clean version of windows to do this type D:\setup or install and that should work, and 1 last thing make sure you go back into the bios and change to bootup sequence back to IDE-0 first then CD-Rom and then floppy and also turn floppy seek off.
Hope i have been of help to you.
If that doesn`t work post a reply to me here and i`ll try to find another way.