Yes,you can change the orientation of the monitor by applying the options from your graphic(video) card settings.
Different graphic card manufactures and their drivers may have different interfaces. But you always can:
1,go to "control panel" from "start" of your XP system
2, select "display"
3, click "settings"
4, click "advanced"
5, click the tap on the NEXT TO "color management", it is the tab that links to graphic card's advanced property, click the button in the middle may named as "graphics property" or "...control panel" (all depends on the type and model of the graphic card you using, just a little bit different, should be very easy)
6,then you can modify the screen orientation from new popped window. commonly they use "rotation" or "screen orientation" on their tabs.
if you cannot find the option from step 6, please update the newest software from your video drive manufacture's website, you can find the information on the manufacture and model from step 2 by clicking " Adapter" tab.
email me firstname.lastname@example.org if you need more info, good luck!