In order to minimise the disruption that may be caused you will need a business continuity plan in place. The basic plan that most companies use is to backup data on to tape and to store the tape off-site.
If you ever need to restore your data from the last available tape you could be without a fileserver and data for at least 3 working days. This is an estimate based upon the assumption that the backup tape supplied works and that there is a replacement fileserver available.
Our proposal is that you have a replacement server stored off-site which is regularly tested with your backup tapes. In the event of a need we can restore your latest available backup tape to the server and install this unit on-site within 7 working hours. All that is then required will be to connect the workstations and printers to the new server.