I got one.... Called "NOTEPAD!"!!! No but on a surs note. I really wish Apoc would update his to cata and all that jazz.
Honostly i thought notepad was what most people used lol i didnt seen any mention of a actually program to create .xml
You could also look up "Notepad 2" It'll highlight the tags and all that, and arrange them to be all pretty. It works for a lot lot more than just .XMLs also.