This entry is more so I have a easy to reference link for answering "how do I monitor my DB" questions that always crop up.
Using and installing
statspack for oracle10g Now called AWR but the statspack stuff is still there and is included, AWR is a extra cost option I believe.
I can't find any online documentation for installing statspack in 8i.
But in 8.1.6+ if you read $ORACLE_HOME/rdbms/admin/spdoc.txt it tells you pretty much everything you need to know about statspack.
The spdoc.txt script exists in all versions at the same location in the oracle home.
If you don't use statspack - learn it and use it.