Yes it will sync ok with it but expect increased latency during streaming especially if this is running across the same network used for internet access, if you get someone downloading or online gaming while your trying to stream a movie from your Ethernet hard disk to the media centre and tv you could end up with an experience such as high quality you tube

long pauses and everything

Are you running gigabit network cards eveywhere, what is the card and drive in the Lacie are they fast enough to supply data in your environment?