I have a folder a/ and a remote folder A/. I now run something like this on a Makefile:
get-music:
rsync -avzru server:/media/10001/music/ /media/Incoming/music
Since the original question also involves a desktop and laptop and example involving music files (hence he's probably using a GUI), I'd also mention one of the best bi-directional, multi-platform, free and open source programs to date: FreeFileSync.
It's GUI based, very fast and intuitive, comes with filtering and many other options, including the ability to remote connect, to view and interactively manage "collisions" (in example, files with similar timestamps) and to switch between bidirectional transfer, mirroring and so on.