many xml parsers are built into Python. Documentation is available:
http://docs.python.org/library/markup.html

I usually prefer ElementTree:
http://docs.python.org/library/xml.etree.elementtree.html

here is a simple example, adapted from the web:

from xml.etree.ElementTree import ElementTree
tree = ElementTree()
#this reads in the xml data from a file:
tree.parse("index.xhtml")
#

p = tree.find("body/p") # Finds first occurrence of tag p in body
p
#
links = list(p.iter("a")) # Returns list of all links
links
#[, ]
for i in links: # Iterates through all found links
i.attrib["target"] = "blank"
tree.write("output.xhtml")


this approach seems to work better:
from xml.etree import ElementTree

f = open("evernote_export-20110809.enex")
root = ElementTree.fromstring(f.read())
print root
root.items()
root.findall('note')