Opening of .dat files

DAT files are usually data files created by an application.

You need either the specific application, or one with the proper filter to retrieve the data.

If this does not help.
Please provide more details as to what you believe is in the files, or what the application is.

You might try this program:

http://www.irfanview.com/

to view the file contents.

Chas

Sometime Dat Files Are Data Files Or (Vedio Clips, Movies) Files.
So that you might it Open With MultiMedia Player or the Software it came with

I use a program called NoteTab Pro, it's similar to Microsoft's Notepad but many more features, anyway when I'm using this app it auto saves whatever I'm working on every 10 min & it saves it as a .DAT file.

To open the file in question, open up Notepad & click on File & select open, this should open another a directory search window just navigate to the file you want to open & select it, if the file is to large to open with Notepad do the same with MS Word if you have it, you'll likely onlysee code that won't make any sense anyway, buts thats how to open a file without messing up any file associations on your PC.