More file questions! Please help.

Ok, I have another file question like the one before. How can I make a program that will do different things when a certan file is located in the same dir. as it? Such as a dialog based program that will load a different dialog if that file is found in its same location. Almost like installer programs do that when you have installed the software, then the next time you run the setup.exe program you can now uninstall the software. Any ideas????

Thanks!
Nathan Strandberg