It's not a matter of software capability, but a license question. MS didn't license MPEG2 decoders for XP, that's all. They changed their mind with Vista and Windows 7.
How can I force XP to use, for example, VLC every time DVD movie is inserted into the DVD Drive?
Check the options and settings of the software, if there is a "make default for DVD playback" checkbox or similar.
You might also check the "Programs Access and Standards" (no idea about the name in non-german Windows versions) applet from control panel.
thanks so far..
You are Welcome