As I said earlier, if you're working with special characters which xml would parse, you can use CDATA sections or do this:
<xsl:value-of select="." disable-output-escaping="yes"/>
This will preserve any HTML tags you have in your node. Please note though that this will not produce well-formed xml (or in this case xhtml).
If this is what you're looking for, I can send you a simple but complete example on this.
You might as well just check out some French site on xml.
Or you can email me in French about your xml questions, I can deal with it.