You can also network a mac and pc together. This is actually pretty easy and fast because you only have copy the file once and often you can use gigabit ethernet, which is faster than firewire or usb.
Check out how to do it at the bottom of this article:
http://magazine.creativecow.net/article/21st-century-cinema-an-indie-look-a...
-Russ
Russell Lasson
Colorist/Digital Cinema Specialist
Color Mill
Salt Lake City, UT
www.colormill.net