xml help

hello there
I'm making a message board using PHP and XML
PHP is ok, now I need some help with XML since I'm a n00b

I want to make something like this:

[what's your favorite color?]
user1: orange rocks
user2: I love blue
>>> user3: you are a terrible fagot
>>>>> user4: no he's not, YOU are!
>>> user5: I love blue too

I hope you get the idea
I'm not sure how the XML should be, my idea is:

<entries>
<entry>
<user></user>
<text></text>
<replies>
<entry>
<user></user>
<text></text>
<replies></replies>
</entry>
</replies>
</entry>
</entries>

and then just tell CSS to move <replies> to the right

but I am not sure if this is correct

thanks

A XML-backed board system is bound to be the fastest as hell. I wonder why no one else had this idea before!