SharePoint 2010 Linked Data Source item link field

For Direct Page:

<a href="{@FileDirRef}/DispForm.aspx?ID={@ID}" ONCLICK="GoToLink(this);return false;"><xsl:value-of select="@Title" /></a>

For Popup:

<a href="javascript:OpenPopUpPage('{@FileDirRef}/DispForm.aspx?ID={@ID}');"><xsl:value-of select="@Title"/></a>