Schedule a sqlplus session on the server using cron. Have the sqlplus script always spool the file to the same name, then have the shell script rename it.
Install openSSH on the server and the client. If the server already has SSH then you don't have to install it there. You can use rcp and rsh but since they aren't secure you are better off just going with openSSH.
I installed cygwin then downloaded and compiled the SSH source w/out problems.
Create a scripts on the client to retrieve files from the server and remove them when they have transmitted successfully. (Use scp to copy the files by filespec, use ssh to rm the files that you download)