can i make maps for rpgmaker xp games?
Not really. It doesn't have a direct export to RPGMaker room files, and even if it did, RPGMaker has a limited number of layers, which Tiled is capable of exceeding. If you're stubborn enough, you might be able to find some way of doing it, but wouldn't it just be easier to make those maps in XP? Its map editor is very intuitive. I believe Tiled was designed to help make map and level editing on things like GameMaker, whose tile editor is notoriously trash, much more bearable.
Tiled was designed as a generic map editor, so that game developers would spend less time building their editors and more time creating their games. That it also provides an alternative to proprietary editors like the one found in GameMaker is a nice plus. :-)