I thought I'd blog about a great affordable piece of Windows Software: MirrorFolder. It provides a software level real-time RAID-1 mode that can backup files in real time, and I am also largely using the option to auto-synchronize my backups upon connection of my USB hard drives. There is also a whole bunch of options for fine grained configuration.
The 4.x version now includes a centralized GUI that is a great complement to the Windows shell integration (right click on a folder to configure its backup strategy).
Get it from Techsoft. It's 39 US$ so close to just 20 euros these days. Lucky me.