Local server and repository (Meta Data) packages are both stored in the
msdb database, so by backing this up you also back up your DTS
Some people prefer to keep copies of their packages as file packages,
which will obviously be covered by your normal file backup routine.
Use the Save As option in the DTS Package Designer to save packages to
file. You can use the package SaveToStorageFile method to automate this
process, but be aware that this does not persist the layout or annotations.
Local server packages are stored in the [msdb].[dbo].[sysdtspackages]
so you can take the additional precautions of exporting this table to a file.
For more information on sysdtspackages see
The DTSBackup 2000 tools can be used to automate this