As long as they are connected to the same network and are in the same workgroup, it's a walk in the park using the SMB protocol. Google will throw up hundreds of tutorials on the subject.
As for other methods such as ad-hoc ethernet, firewire or USB transferring, I''m not sure how, but I'm sure it's possible
Edit: If this is a one-time transferring, and you have no interest in synchronising or anything of that nature, you could always throw the data on a USB stick or an MP3 player (the iPod in disk mode works an absolute charm for this)
*av