How can I take advantage of a dual-processor?

I'm running Oracle7 Server on a dual-processor WindowsNT server. Most of the time the first processor is overloaded and the second = processor
is idle.
How can I take advantage of a dual-processor Server? Should I have 2 Oracle7 Server instance running on the same Db files? Should I use 2 Listener processes to share the Oracle7 Server processes = on the 2 CPU?
Should I use Parallel-Query option to share SQL execution on the 2 CPU? Or what else should I do????

Thanks in advance for helping!

 Luca Minudel                    software designer
 Italy                             Conegliano (TV)
 e-mail                      luca.minudel_at_nline.it
 WWW                       (italian language used)