export a table in package

I have created a package which export a table in SQL2k5 to a dbase file. I created a SQL native client and a MS Jet 4.0 OLE Jet DB provide. I make Source point to SQL native client connection manager and OLE DB destination point to MS Jet 4.0 OLE Jet DB provide connection manager in Data Flow specification. When I try to run the package, it saids all the columns cannot between unicode and non-unicode string data types. Is there any setting I need to change. Please help. Thanks.I solved the problem by adding data conversion task between source and
destination. But this does only for append. How can I do it for overwrite?
Thanks.