Hi

For disaster recovery..I dont really recommend replication..replication is okay if there one or two tables and these undergo some small changes which needs to be available at the other site..You should be looking at Oracle Data gaurd or Oracle standby for disaster recovery..just make sure that the two primary and secondary are at different sites..I maybe wrong here but some of the other DBA's may come up with other ideas perhaps

For system administration you can look for

http://www.sysinternals.com/