The reason why it had placed the files in different places was I belive that the installer was following the OFA (Oracle Flexible Architecture) But still couldn't get why it would go to the C: level instead to start from the directory that you had specified.

Comming to the point of OEM, inorder to run the oem, you would require a OEM repository created in one of your instances. To create the repository, go to ORACLE_HOME/bin and execute the "emca" This would bring up a GUI and would help you to create a repository on your running instance. In the mean time, also make sure that oracle intelligent agent is also started on the server.

lsnrctl dbsnmp_start

Once after you create the repository, you go to strat the oracle management server. On any unix system one would start
it by

oemctrl start oms

Once you start the management serer then you could log into the oem by default username "sysman" and password "oem_temp"
and the hostname where the OMS (oracle management serer) is running. This would allow you to start the OEM and then you have to discover the node to start thing going.

For how to create the repository and etc, go to
[url]http://technet.oracle.com[/url] and do a search on the OEM version that you are running. This would get you a very good resource on OEM.

Good luckl
Sam