Minimum 64 MB of RAM for Main Updates.
160 MB free hard disk space for (ALL) options.
 Install Windows 98 Second Edition (with or without 98lite).*
 Install all drivers for your hardware.
 Install Internet Explorer (any version).*
 Install latest DirectX 9c.*
 Install latest Service Pack 3.x (Main Updates).*
 Install optional components of Service Pack 3.x.*
 Install MS Office.*
 Install KernelEx, 98SE2ME, Revolution Pack.*
[* = Optional]
Before installing U98SESP3.EXE make sure that:
1/ You have the original w98SE installation disc.
It will change core system files. It means that if something goes wrong you must be
prepared to reinstall windows from the beginning.
Sometimes installing U98SESP3.EXE after a fresh install is working normaly while it failed on an old install.
2/ You made a back up of all important datas.
It's extremely unlikely that an error forces you to reinstall windows and
eventualy to reformat thus to erase your hard drive.
But for the sake of safety, please do it!
3/ You made a back up of your system files
A copy of the "windows" and "Program Files" directories, at least the "windows" directory,
preferably on a second physical hard drive or on CD or DVD or an external drive.
This is usefull to revert back to a prior w98se install which was already
updated and functioning well.
Restoring windows 98 can be done simply be recopying all the system files back to their original location,
in dos mode. The easiest way is to use a second physical (not a partition) and internal (not USB) hard drive.
It's aslo a good idea to make sure a copy of the registry has been automaticaly preserved in the system files
you backed up and to know how to restore the registry in dos: boot in DOS, then type SCANREG /RESTORE.
4/ You have time and patience to read all the instructions
If you are somebody who will select all options no matter what they are
or who will click "OK" instead of "Cancel" on any dialog box without knowing what was the question about,
then you are sure to run into trouble.
Don't do it in a rush. If words are written on the screen it must be important. Please read them.