Oracle 10G DB Control Reinstall on 10G R1 and R2

Reinstallation is different in R1 and R2 (on Windows xp)

on R1:
uninstall with the cmdline tool emca:
emca -x SID
reinstall again with java based DB Config Agent:
dbca

in spite of a "sys as sysdba" login in sqlplus is working,
after installation of the DB Control there may be the
need to do a alter user sys identified by xxx (same password)
to make the login work in the DB Control.

on R2 all can be done with emca:
emca -deconfig dbcontrol db -repos drop
install again goes with:
emca -config dbcontrol db -repos create

for additional infos see
Configuring Database Control with EMCA