Hi Francisco:
I work with Linux and SAMBA as a fileserver and it works fine. I don't have too much experience with linux but it's easy to implement. Red Hat and other distributions installs SAMBA and SWAT that is a visual config utility.
So if you have 900 clients I think that is better for you to use a database server such a MySQL, you can administrate it with the powerfool PHPMySQLAdmin an it is very fast and stable. You can connect your VFP via ADO with tho ODBC driver for MySql.
HTH.
Pedro