Visual Studio WebTest Viewer is a portable tool which reads VSTS WebTest XML into familiar tree structure.
It could be used to open WebTests exported from Fiddler.
Due to its small size it can be placed on the USB stick and run from any PC with .NET framework installed.
If you are interested in using Fiddler with VSTS 2010 (or earlier) for recording WebTest you can find detailed guide on my personal blog
Using Fiddler with VSTS