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