Oracle copy DB from one windows server to another
Sounds like a data pump using a network link would do the job.  It's always preferable to run it during quieter hours but if your source database is not under powered then you might be able to run it during regular hours without your user's noticing any difference in performance.

From the article


create a database link from the destination to the source
grant EXP_FULL_DATABASE on the source database to the user in the link
grant IMP_FULL_DATABASE on the destination database to the user with the link OR grant DATAPUMP_IMP_FULL_DATABASE role to the destination database user

impdp test/test@db10g tables=SCOTT.EMP network_link=REMOTE_SCOTT directory=TEST_DIR logfile=impdpSCOTT.log remap_schema=SCOTT:TEST


Things to investigate 


the PARALLEL options which will speed things up.   
any custom tablespaces on the origin database?
are you going from the same character set to the same character set?
you do have a development environment to test this..