Data Transfer
You can transfer data directly between computers if they are on the same network, or you can use a special USB transfer cable.
Mac over Network
http://support.apple.com/kb/HT1549
Windows over Network
http://windows.microsoft.com/en-US/windows-vista/Copy-files-to-another-computer
Windows 7 options
USB cable
http://www.amazon.com/Medialink-Transfer-easily-between-computers/sim/B004LCBCM8/2/ref=pd_cp_e_sexpl
USB drive
If you are having trouble with the above methods you can use the old fashioned "sneaker net". Place the data on a USB drive and walk it over to the other computer.
For data transfer across distant networks see File Sharing