Is there a thumbnail viewer for window 7 for the Canon mxf files?

Yes, use Canon XF Utility. :)

Thumbnails, playback and more: Canon U.S.A. : Downloads (http://usa.canon.com/cusa/professional/products/professional_cameras/cinema_eos_cameras/eos_c300?selectedName=DriversAndSoftware)

Hé Roger, long time no see.
Once the files are on the pc i cannot view them in XF utility.
Bridge does not show thumbnails.
So last option is Windows Explorer.

Once the files are on the pc i cannot view them in XF utility.
Are you using File > Set Virtual Media to point XF Utility to the CONTENTS folder? (It is not possible to point XF Utility to individual clips.)

If you place the CONTENTS folder inside another folder it should be possible to view the files. For me this works: D:\ProjectName\Media\Card_01\CONTENTS

I am not at the edit station now, but if i remember correctly i just use File > Set Virtual Media to the Card_01 folder.

Glad to see you here Ann! :)

Thanks very much. I was fiddling with the Virtual Media, but now the Contents are in a folder it works.
Thanks again.
Ann

You're welcome! :)