You can easily convert the TGA's to PNG with SageThumbs.
http://sagethumbs.en.softonic.com/
You just select all of the textures.
Right click on one of the selected textures.
Search for SageThumbs in the list and Choose the option to Convert to PNG.
Now you have all of the textures in PNG format.
Now delete the TGA textures and you're done.
http://sagethumbs.en.softonic.com/
You just select all of the textures.
Right click on one of the selected textures.
Search for SageThumbs in the list and Choose the option to Convert to PNG.
Now you have all of the textures in PNG format.
Now delete the TGA textures and you're done.