
Installed Virtualbox and the extension pack on windows 7 64 bit OS. It took no more than five minutes. Now to figure out what vm appliances to start with.
Here is the link I referenced: http://www.virtualbox.org/manual/ch01.html#intro-installing
I will try Mac OS X on Virtualbox at a later time. Right now I will try the "OTN Developer Days" image.

Link for Developer Days Appliance: http://www.oracle.com/technetwork/database/enterprise-edition/databaseappdev-vm-161299.html
More helpful links:http://forums.oracle.com/forums/thread.jspa?messageID=9593427&tstart=0
So far:
1. Installed Virtualbox with extension pack
2. Imported the OTN Developer Days Applicance
3. Confirmed orcl database was up using sysdba
4. Created connection in sqldeveloper for orcl and tested select to dual.
linux userid/password: oracle/oracle