I was never able to get a back-up of the 3650, it would always stop
half way thru.

You can transfer them to the memory card, then read the memory card
with your computer.

It's how I do it, just much easier to take the card out and read it

As for reading the info in a DAT file or any file
Ultraedit text editor works well.
http://www.ultraedit.com/

and PEEK to just view/grab the text out of a binary file
http://members.ping.at/mlubich/

--
Microsoft Will Help Deliver a "Better" Linux
Remember Lindows?
http://www.linspire.com/linspire_letter_archives.php?id=48

We can suggest to have a look at Oxygen Phone Manager II for Symbian OS phones ( http://www.opm-2.com/symbian/ ). Its business version allows to export the phone's data to various formats.

PS: it extracts the data from the phone itself, not from a backup made by other software.