Normally you can't install the OEM Version of Windows98 if you have an existing Win95 on your system.
To get around this problem:
Boot the PC with the Windows 95 Emergency Startup Disk to the MS-DOS prompt but make sure your CD ROM drivers are loaded on the disk and have access to the CD_ROM drive.
Run the MS-DOS editor EDIT and create a dummy file NTLDR (no extension) in the root dir C:\\ In the Windows95 directory (usually C:\\WINDOWS), rename the file WIN.COM.
Start the Windows 98 Setup with: SETUP.EXE /NTLDR
You will be prompted for the directory to load Windows98 into, by default if you already have Windows95 loaded and are upgrading, it will have c:\\windows.000 make sure you change it to c:\\windows or it will load Win98 in another directory.
