Shutdown all Oracle Windows services

Install 10.2.04 patchset (run setup)

Startup all Oracle Windows services

from CMD prompt: sqlplus /nolog
from SQL prompt: connect sys/sys@db as sysdba
after connect:
shutdown immediate
after shutdown:
startup upgrade
after startup:
@oracle_home\rdbms\admin\catupgrd.sql

after script finishes (it could take a while)

@shutdown immediate
after shutdown:
startup upgrade
after startup:
@oracle_home\rdbms\admin

You are now upgraded.