[XeTeX] Problem changing default fonts

[Drébon]

Hello,

     I recently tried to convert my latex documents to xelatex... I 
turned to xelatex because I needed to have some utf-8 processed things 
in the preamble.

     I encountered a problem with converting the font choices I made. I 
used the following packages :

\usepackage{marvosym}

\usepackage{pxfonts}

\usepackage{txfonts}

\usepackage[osf,sc]{mathpazo}

\usepackage[scaled=0.85]{beramono}

\usepackage[euler-digits]{eulervm}

\usepackage{helvet}



%\usepackage{microtype}

\usepackage{textcase}

\usepackage{soul}



The first group of packages are used to change the fonts. But if I use 
the xltxtra package, they have no effect.

On the other hand, if I do not use xltxtra package, the œ character is 
not accepted and thus 'cœu' becomes 'ceur'...

I am looking for a solution letting me define the same outlooks as 
before but with xelatex and that accepts the œ character.

As anyone such a solution ? Thank you.


-- 
Best regards, D.