xml tree

Hi,
I need to build an XML tree using the XML output from a SQL Server query. The data is from a single table that refers to hitself with a parent_id > id link to define a hierarchy.

So there's 2 questions;

(1) How do I do this in SQL server (all my data queries are coming from stored procedures)

(2) Once I have the data in an XML tree, what's the best way of processing it using an XSL file to build the tree as HTML ?

thanks in advance

Andy