I see, so you're trying to always get the barcode first because then it will always be in the merged field.

You could easily merge the 2 fields with a slight mod to the stylesheet, for example using:
instead of
XSLT is tailor-made for messing about with XML without resorting to writing your own parser. On windows you can easily run transforms with a bit of javascript or vbscript run through windows script host. there's tons of examples out there, I bet there's some stuff on w3schools about it...

Just had a quick google around and you can still get MS's command-line program to run the transformations from http://msdn.microsoft.com/en-us/library/aa468552.aspx. Then its as easy as: MSXSL –o out.xml in.xml reformat.xsl

That is a neat line. Looking back I should've tried something like it myself. I almost did, but I decided to try my hand at awk instead (I've just finished reading through the Unix Grymoire and I'm trying to learn more about both programs).

The nice thing about it is that it uses the little-known sed hold buffer. To break it down, assuming I'm reading it correctly, the first part of the command matches the line '<ItemTitle>', then grabs the next line following it as well (the N command), stores them both in the hold buffer (h), and deletes the pattern space so that it can go on to the next command (d). The second expression then matches the <ItemBarcode> line and appends the contents of the hold buffer to it (G). That's it.

Actually, I think the real reason I went with awk was that I was having a bit of trouble understanding exactly how sed's hold buffer works in practice. This real-world example has helped a lot.