Dmoz xml structure sort

Hi all.
I have a navigational site tree xml page similar to Dmoz.org.
And its made up like this below. I am new to xpath and am having problems
finding a solution to this.

My file looks similar to this.

<Topic id="Base">
                        <tag catid="1"/>
                        <Title local="en-US">Home</Title>
                        <narrow resource="Base/General_Information"/>
                        <narrow resource="Base/StudentLife"/>
                        <narrow resource="Base/Missions"/>
                        <narrow resource="Base/Community"/>
                        <narrow resource="Base/Academics"/>
                        <narrow resource="Base/News"/>
                </Topic>
                <Topic id="Base/General_Information">
                        <tag catid="2"/>
                        <Title local="en-US">General Information</Title>
                        <narrow
resource="Base/General_Information/About_us"/>
                        <narrow
resource="Base/General_Information/Contact_us"/>
                        <narrow
resource="Base/General_Information/Directors_Letter"/>
                        <narrow
resource="Base/General_Information/History"/>
                        <narrow
resource="Base/General_Information/What_We_Beleive"/>
                        <narrow
resource="Base/General_Information/Staff_Directory"/>
                </Topic>
                <Topic id="Base/General_Information/About_us">
                        <tag catid="8"/>
                        <Title local="en-US">About Us</Title>
                </Topic>
                <Topic id="Base/General_Information/Contact_us">
                        <tag catid="9"/>
                        <Title local="en-US">Contact Us</Title>
                </Topic>
...
...
...


And I want to acheave results like this if I had a dynamic variable like 
"Base/General_Information/About_us"

<Topic id="Base/General_Information/About_us">
                        <tag catid="8"/>
                        <Title local="en-US">About Us</Title>
                </Topic>
                <Topic id="Base/General_Information/Contact_us">
                        <tag catid="9"/>
                        <Title local="en-US">Contact Us</Title>
                </Topic>
                <Topic id="Base/General_Information/Directors_Letter">
                        <tag catid="10"/>
                        <Title local="en-US">Letter From the
Director</Title>
                </Topic>
                <Topic id="Base/General_Information/History">
                        <tag catid="11"/>
                        <Title local="en-US">History</Title>
                </Topic>
                <Topic id="Base/General_Information/What_We_Beleive">
                        <tag catid="12"/>
                        <Title local="en-US">What We Beleive</Title>
                </Topic>
                <Topic id="Base/General_Information/Staff_Directory">
                        <tag catid="13"/>
                        <Title local="en-US">Staff Directory</Title>
                </Topic>

Can someone point me in the right direction?
john