I've been considering carrying my Windows XP virtual machine between my desktop iMac and my laptop. Last night I copied the 25 GB virtual machine file over by using Target Mode. It took about 20 minutes. It wouldn't be practical to do this every day. Ideally I'd like to keep it in sync similar to the way some backup programs do. Is there a way to have only the incremental pieces that changed in the file copied back and forth? I'm using VMware Fusion.