Writing a programs to read .Dat files using VB

I'm writing a program for a Client, he has got some data saved in .dat files, I wish to import all that data in a readable format. Does anyone know how can I do this???????????

VB Code:

Open "file.dat" for Input as #1
     Input #1, Data
Close #1

Of course, it may not be this easy if it's an intense file, or encrypted.