I tried it under Windows 7and Kubuntu 10.4.
Whenever I open a tcx file I get an error that the file could not be read or parsed. I also tried the samplefiles from http://developer.garmin.com/schemas/tcx/v2/
But I will also attach my file. The tcx file is to large, so I will attach the gpx file, you can convert it to tcx here: http://www.gpsies.com/convert.do