Splitting a large XML file into smaller ones

I have a large XML similar to the one below:

<BookStore>
<Book>book1</Book>
<Book>book2</Book>
.....
<Book>book1000</Book>
<Book>book1001</Book>
......
</BookStore>

The <Book> element may occur in 1000's. I want to create several smaller XML file each containing say only 250 <Book> elements. As far as I know, the two ways it could be done is either using XSLT or loading the entire XML into a DataSet and then create smaller subset DataSets. Since I am not an expert on either of them, any help is appreciated