The titlebar displays the name of the form (which when it is unsaved is Form1, Form2, etc) and then the name of the application.
If you saved your form as "AV (123343:1995) (3:1)" and then loaded it again, you would see:
AV (123343:1995) (3:1).xml - Microsoft Office InfoPath 2003
Note the addition of the ".xml".
To change it other than that, I believe it is possible since you are using managed code, provided that you have a full trust form. Then you should be able to do whatever it is C# allows you to do to modify the titlebar text. I personally don't know that process, but I'm sure its well documented somewhere in a C# forum.
Good luck.
Greg Collins [InfoPath MVP]
InfoPath Dev