I need some advice/help.

I need to be able to populate a dropdown list box using the contents of a directory.

What api's are available that i can call on or what would be a better way of doing this. again I am not using a database of anysort, i need to traverse a certain directory, collect files that match a certain criteria (i.e all .pdf files in a given directory) and populate a listbox using them. from there i would hava a go button that will basically open the file.

thanks for all the help in advance.