security for online tools, audio converters

[zanoos800]

I'm using an online service that provides a tool to convert my audio files http://www.etyn.com/tools/audio-converter but I know nothing about the safeness of the tool.
the site looks good but how can I make sure that it's secure and if it's not how can it harm my PC??

Any help would be greatly appreciated.

[Curt@invincea]

Run it under Sandboxie.