Parameters or Registry keys? Which is best to tell an application to do "something" at startup?

The registry is probably the better choice.

That’s where “configuration”-type stuff is supposed to go, for one thing, so people are more likely to look for it there. For another, users will sometimes create their own shortcuts to an application, and we don’t necessarily want to have to deal with maintaining some set of flags in order to do so.

(Depending on exactly what you’re trying to accomplish, it might be nice to build in some command-line parameters too, in case power users would want to utilize them..)

Yea, registers were my first option also. Thanks for confirmation AND for the detailed explanation ;)

Thumbs up!

The registry is a good place to keep your configuration information, but you may also want to consider using configuration files (such as INI or xml). Using an xml file, you have the potential for making a ‘portable’ version of your app (if you are ever inclined to do so), plus if you ever have any inkling to port your program to another operating system (such as Linux), you wouldn’t have to muck around with changing registry code to configuration file.