Writing a SELECT with each OPTION a unique value

I'm fairly new to this whole XML/XSL(T) thing.  I've got this XML file.
It's painfully basic, I'm sure you've seen it somewhere online:

<?xml version="1.0" encoding="ISO8859-1" ?>
<CATALOG>
	<CD>
		<TITLE>Empire Burlesque</TITLE>
		<ARTIST>Bob Dylan</ARTIST>
		<COUNTRY>USA</COUNTRY>
		<COMPANY>Columbia</COMPANY>
		<PRICE>10.90</PRICE>
		<YEAR>1985</YEAR>
	</CD>
	<CD>
		<TITLE>Hide your heart</TITLE>
		<ARTIST>Bonnie Tylor</ARTIST>
		<COUNTRY>UK</COUNTRY>
		<COMPANY>CBS Records</COMPANY>
		<PRICE>9.90</PRICE>
		<YEAR>1988</YEAR>
	</CD>
</CATALOG>

What I want to do is write a SELECT with each OPTION being a unique
value, in particular for this XML file: COUNTRY.  As I see it, there's
two ways: using KEYs, using "preceding::" -- KEYs are far faster,
preceding is... well... arguably more straightforward.  I'd like to use
KEYs, but I've run into a bit of a wall.

<xsl:key name="KEY_COUNTRY" match="CD" use="COUNTRY" />
 -- indexes all the items based on country

<xsl:for-each select="key('KEY_COUNTRY', 'USA')">
	<xsl:value-of select="." /><br/>
</xsl:for-each>
 -- iterates though all items and spits out records where USA is the
country

<xsl:value-of select="key("KEY_COUNTRY", "USA")[1]" />
 -- returns bob dylan's record

Is there any way to get a list of the values, e.g.  USA, UK, etc... ?
 kinda like using the "key" function but without the second parameter?

I ended up writing a template like such -- which would return me a
SELECT with a series of options, each being unique:

<xsl:call-template name="selectField">
<xsl:with-param name="currentNode" select="CATALOG/CD/COUNTRY"/>
<xsl:with-param name="name" select="'COUNTRY'"/>
</xsl:call-template>

<xsl:template name="selectField">
	<xsl:param name="currentNode" select="."/>
	<xsl:param name="name" select="."/>

	<xsl:value-of select="$name"/>:
	<select>
		<option selected="SELECTED" value=""></option>
		<xsl:for-each
select="$currentNode[not(.=preceding::*[local-name()=$name])]">
			<option value="{.}"><xsl:value-of
select="."/></option>
		</xsl:for-each>
	</select>
</xsl:template>

But should I be kicking myself in the pants for using preceding?
  Isn't it going to be painfully slow for my users when I get to actual
datasets?

Thanks in advance

-Tyler Waters