Hi,
when you use "unload", you put the result of your select command into an ascii pipe delimited file, supposedly the most compatible format ever for a data transfer. You might have a character codeset issue when importing your data.
unload is the simplest way to export data, and other tools won't be of any help in your case.
try to be more specific on the error given by Oracle, I am sure people here will help more efficiently.
eric