Here's an lxml snippet that extracts an attribute as well as element text (your question was a little ambiguous about which one you needed, so I'm including both):
from lxml import etree
doc = etree.parse(filename)
memoryElem = doc.find('memory')
print memoryElem.text # element text
print memoryElem.get('unit') # attribute
You asked (in a comment on Ali Afshar's answer) whether minidom (2.x, 3.x) is a good alternative. Here's the equivalent code using minidom; judge for yourself which is nicer:
import xml.dom.minidom as minidom
doc = minidom.parse(filename)
memoryElem = doc.getElementsByTagName('memory')[0]
print ''.join( [node.data for node in memoryElem.childNodes] )
print memoryElem.getAttribute('unit')
lxml seems like the winner to me.
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