Automatic incremental backups to flash drive

I will be overly detailed, as I would like to get an overly detailed response. I have a laptop running WinXP sp2. I would like to be able to plug in an usb key (8GB Sandisc micro) to the laptop and have it automatically copy folder x from the laptop to the usb key. There would be nothing on the key but whatever program does the copying and folder x. I can say that this will be the only computer this key ever is plugged into and it always shows up as the same ‘E’ drive letter. I would like(if possible) to have it save the file as an incremental backup each time ie; filename1, filename2, etc. I am not worried about encryption or compression as the files needing backup are neither large nor sensitive. I would like the process to be silent and automated. I have thought about creating an autorun file that will launch Toucan; letting it do the copying, however I really know nothing about creating scripts for Toucan so I am open to suggestions. One thing that I would like is to make sure the program that does the copying is contained to the usb key, and follows PortableApps.com standards. I feel like I am probably overlooking some easy solution. I would appreciate any input from the community, and sorry about the lengthy post, I wanted to be thorough.