I have a copy of nero premium which has a sync feature but have heard microsofts http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx (synctoy) is useful for same.
Free, and works well. Installs on Laptop, and can set it to run whenever laptop is fired up. Includes exclusions - e.g. copy everything in My Documents, but exclude My Music folder etc.