OpenOffice.org does seem the way of the future, and you are right to be excited about OOo's use of XML. Look at http://xml.openoffice.org/xml_advocacy.html
for more information there. I'm still not exactly clear on what Access can do that Calc (the OOo spreadsheet and database user tools program) cannot. But as for MSWord vs. OOo Writer, I would go OpenSource all the way.