[Farling]

There is an updated version of the xls1.xslt file available which should work slightly better. However if you aren't getting the file selection dialog appearing then there is something more fundamentally wrong.

Can you try running powershell.exe directly from the start menu (Or press Windows+R and type powershell.exe into that box)?
Then "cd" to the directly with the downloaded scripts and type in the command:

cat .\convert.ps1 | powershell.exe -noprofile -

This should try to run the script. If it produces errors, then could you send me a copy of the errors so I can trace the problem.

(I'm not sure if there is a Windows .NET item which needs downloading in order to use this script properly.)