Auto vs 100Fdx. Which to use?

Hi All. Auto negeotiate or 100 Full Duplex? Which is the best option to set both NICs and switch ports (HP Procurve). I would say AUTO, but my colleagues think that the 1980’s problems with old 3COM NICs with auto-negeotiation problems still applies today. In regards to normal LAN operations and Tape backups over the LAN (TCP/IP network) which is the best practice approach — auto or 100Fdx? Ideas/suggestions/concepts/proof? Thanks in advance.