Via a comment, Pieter Overbeeke informs me that he has a script for downloading files and controlling iTunes for Windows XP available! This does the same stuff as get_enclosures or iPodder on the Mac, by getting the files and also adding them to the iTunes library.
In the shower this morning, I was wondering if there were COM libraries for Perl that I could use to control Windows iTunes from get_enclosurest. Now that Pieter has invented this wheel, there is no need. If you are on Windows you should definitely give his script a try. More infrastructure for the “iPod platform!”