Having had problems with uploading web files using filezilla as an ftp client, I solved it by dragging and dropping the files to Filezilla rather than importing them and it worked fine for whatever reason. I have since discovered, and this may have been general knowlege to everyone except me, that you can up load your files using Internet Explorer and simply add your web space as a Network Place ('Location' in Vista) and so simply drag and drop revised files too that 'network place'.
This is very useful if you are doing regular updates/revisions.
If this is of interest and not general knowlege to every one but me I'll outline the steps if required.
Derek