DropUpLoad is a free light Windows utility, which manages your uploads in the way of a spooler. To use just copy the exe file and double-click, it's ready! It can also run when copied on an USB device.
You can create as many servers as you wish. They will appear in a combo box at the top of the window of DropUpLoad. Then select a server, and drop your file in the central rectangle. The file will be added to the spool list and the upload will start as soon as possible, accordingly to your connection and server availabilities. Each file can have a different destination if you change server between each drop. DropUpLoad is undoubtedly the simplest way to update your site.