Transferring Large Files between Vista and XP over an Ornery Network Using the Mac OS X Finder
Assuming your Vista and XP machines are communicating happily enough to see each other and you own an Apple on the same network, go to Finder and hit command + k. Type in the name of the Vista server as smb:// followed by the name of the computer as it appears on the network. Note that this is the same name as you would use in Explorer; i.e. \\ComputerName. Do the same for the XP machine. Now transfer the file between your Windows computers through Finder on your Apple.