Disabling Indexes and Auditing for large data import
Disabling indexes is a popular method when inserting a bulk amount of data.  So if you are looking to get this done in the shortest amount of time (your window isn't long enough for the with-index import??), simply do this:

alter index YourNonClusteredIndex
on YourDestinationTable
disable
go


Do this for your nonclustered indexes.

Granted, when you disable your indexes (provided you want to continue to use them) to enable then you'll need to rebuild or recreate them.  So there is that time-consuming side effect.

Another consideration pointed out by @JNK:


  Just disabling indexes on the table may be an issue if he uses any of those indexes to find the row to update or check for a previously inserted row.


In other words, whatever you choose you should be testing to ensure you're getting the gains you are looking for.

As for auditing, you need to be more specific on what type of auditing you are using.  If you have triggers on your table, and that is your auditing design then you can also disable all of the triggers on your table by doing the following:

disable trigger all
on YourDestinationTable
go


Disabling the triggers on a table could potentially save you a lot of time on your insert (or whatever action fires the trigger[s]).