Try this:

<xsl:attribute name="href">
   <xsl:value-of select="RRLInfo/IMIInfo/IMISource"/>

Because the text is not all ignorable whitespace, you need to be specific about which part is significant or else it will all be included.  MSXML is giving you the wrong results, even though it happens to be what you want. 
Correct. Or, if you prefer, write:
<xsl:attribute name="href">
  <xsl:value-of select="concat('.', RRLInfo/IMIInfo/IMISource)"/>
Michael Kay 

Teresa Rippeon wrote:
I have the following code in my XSLT to get an expected result of "<a href="./Media/Helipad2.avi">Video on Deck, VD1.1</a>".
      <xsl:attribute name="href">
               .<xsl:value-of select="RRLInfo/IMIInfo/IMISource"/>
      <xsl:value-of select="$MaterialText"/>
However, I get the result of:
"<a href="%0A%09%09%09%09%09%09%09%09%09%09%09./Media/Helipad2.avi">
                            (View Video on Deck )

Chris P. McCabe               - Principal Engineer
Choice Hotels International   - Information Systems - 602-953-4416