You do not need samba to share a printer between two linux machines. That is the hard way.
Make sure cups is installed on the client, the server ( Mandriva ) should have it installed now, since you can share the printer to windbloze machines.
In cups, on the client ( Ubuntu ) install the same driver as you did in Mandy. Open a web browser, and enter http://localhost:631
on Ubuntu. Now add your printer. You can ask the system to search for printer, it should find it. If not, you will have to do some PD, ping to verify network connectivity. Post back if you have problems.