Windows servers do not have to be part of any domain or even be on a network in order to run Oracle. A workgroup should work fine. Technically, not all Windows releases are supported with Oracle8i, so if you have problems on an unsupported release, it might be the case that it just won't work.
If your installation went fine and you didn't encounter any errors, then you
should be able to login to OEM. Normally, the default installation will not
install an OEM Management Server and you'll have to use DBA Studio to connect
directly to a database. The default password for the SYSTEM account in the
database is manager. Even in isolated development environments, I'd strongly
recommend changing the default passwords. The best reasoning I can provide
for that recommendation is that it will help establish and maintain good
habits in all environments even if this environment isn't "important enough"
to worry about it.
This was first published in June 2004