I used filezilla before, but maybe due to poor internet connection, the transfer isn't successfully sometimes..
why not try the picworkflow? created by one guy who is active here too..
http://www.picWorkflow.com/?by=219I had a simple guides of how to upload through this website..
http://wp.me/pPDGb-39one thing that is good, you upload one time, and the files will be assigned to different websites even you are off the internet.
there is a promo code 'microstockgroup', so u got 100 credits to try..and there are ways to earn credits too..
so far, i find it is much more efficient than ftp and other uploading method.