Which windows are you going to put on it?
What is on the floppy disk?
If it's Win98, you should be able to boot to the floppy. Type in 'fdisk /mbr', then just 'fdisk', delete all the partitions, create a new partition for windows, press esc to get out of that, reboot, then type 'format c:' at the A:\ prompt. (single quotes for emphasis, don't use them in the actual commands)