JPG exchange between OSX and Windows

I have to set up an efficient way to allow my clients to browse through hundreds (and more) fotos on their computer (some on Mac, more often on Windows) and rate them with 1 to 5 stars. What’s the best software to let me set up the fotos on my side, give the fotos a first rating, let the customer do their choices and send it back to me with their markings?

I am on OSX Lion, I have Adobe Bridge as my main organizing tool, I have iPhoto, too, but already between Bridge and iPhoto the recognition of stars doesn’t work. I cannot expect my client to buy the Adobe Creative Suite and I am not sure if Bridge exists as a stand-alone.

Thank you for your help

cheers

Goso