Writing App Testing software

Guys,

I maintain a very large order processing system. We test every change we make to the software. As always, there are not enough resources to test every possible iteration within the app every time we make a mod. So I am considering writing my own testing application

The way I would like this to run is to have standard commands and data stored in a database along with expected results. The testing app would read a line for each case, perform the functions in the app (which would be running) and then evaluate the results in terms of the expected lines in the database tables as well as the gui.

I'm OK when I'm coding inside my app, but when it comes to calling another running program and sending data to and from same, I'm weak as hell. Can you guys give me just a kick-start as to what might be the best way from "Testing App" to send strings, Keystrokes etc to "Order Mgmt App" and then Read the various Text boxes, Combos, etc to verify results?

As always, thanks for the help.

Tom

The SendKeys statement :)