I am a little confused myself here so I will do my best.
Windows and Word are two different things;
Windows is the operaing system and runs the pc (it tells all the componants how to work together) and as you have Windows XP you have the latest version.
Word is a program called a text editor that creates text documents. Now here comes the problem Word 97 is a good text editor and for most people they will not need more than it can do. They are now sending you Word 2000 that does the same but with some extra bells and whistles most of which you will never use. As for getting Word XP you probably would'nt notice the difference from Word 2000 unless you had the full Office program.
The 97, 2000 and XP just tell you the version of the program you are using.
My personal opinion is that they should have supplied you with Word 2000 in the first place but since they are now getting it to you its not worth grumbling about, and since this is the version you are learning on at school its the best one to stick with.