Always make regular backups of important data. Always try to keep a copy of your data on the company server or another computer to minimize the risk of loosing it.
The reason for the above statement is quite obvious. File servers are backed up regularly and are often running on fault-tolerance hardware such as RAID which reduces the risk of data loss due to hardware failure. Your PC or laptop on the other hand, does not have these features.
If you are saving your data solely on your PC, your information is exposed to a great deal of risk. If the PC is stolen or if it crashes, you might loose all your valuable data. Just imagine the time needed to recreate all documents located on your computer.
Laptops in particular, should use the “Offline folders” feature available in Windows 2000 and newer, to automatically synchronize data between the server and local computer.
You could also use different media to backup your data, and where file servers are not available; such as a home or small office environment. CD-ROMs, DVDs, or ZIP-drives are good backup media that is quite manageable. Remember though, these types of removable media are error prone, so remember to update the backups often.