I've found a way to do the conversion McShea98 details, with less work. I've learned that there is a conversion tool, gpsbabel.exe, that is included with Google Earth. I got a newer version and by using it, I can do the conversion in fewer steps. In short, they are:
1. get your tracklog into .gpx (or .igc or other format that gpsbable knows)
2. have gpsbable convert it directly into the .csv file McShea98 describes.
3. import that .csv into the sample .kml
4. open the resulting .kml in Google Earth.

You'll end up with a Path placemark, with extruded vert. lines linking each trackpoint to the ground (you can easily turn that off in the sample .kml).

I've attached a zip file with all the components and documentation to get this working.

I had to hunt around and experiment a bit with the style sheet that is required by the xcsv conversion. Anyone more intimate with this can improve on this.

Ernie Camacho