They are both connected to the same home wireless network and can access the Internet. I want raspbmc to play some videos that is on my laptop. Should I use NFS or Zeroconf or some other scheme?
I've gotten best results with NFS because then XMBC will index the videos properly, but DLNA will also work fine.
If the laptop is always going to be on when the Pi boots then use entries in /etc/fstab to mount them. If not then DLNA might be simpler as if the laptop isn't on it won't affect the operation of the Pi at all.