All files will be lost, make sure to backup anything important before formatting!
TO INSTALL Windows98:
-Start your comp and enter your BIOS (press either F9,F10,F11,F12 or the DEL, pretty soon after powering up your computer)
-In your BIOS, make sure A: (floppydisk drive) is the primary boot device; look for a setting called "boot sequence" in the standard CMOS menu.
-Save settings, put in your bootdisk and the 98 disc and reboot the comp
-select "boot with cd-rom'
-type "format c:" (if d: is your windows partition type format d: etc)
-type "setup" or "setup.exe"
This is pretty much all info you need.