Agree with Vehelpfulguy, a memory stick is quick and easy. I use one all the time to transfer files between my laptop and PC. For large files, it's usually quicker than using my home network!
If you have Windows XP (I don't know about other systems) you can transfer files directly from one computer to another. You have to connect the two computers via the 9-pin serial sockets.
You go to START, then ALL PROGRAMS, ACCESSORIES, SYSTEM TOOLS and then FILES AND SETTINGS TRANFER WIZARD and follow the instructions.
i recently moved 40gb of music from my dated tower to my new shiny laptop.
I plugged the ipod in to the usb port and closed i tunes. Opened my computer and then opened the ipod (found under removeable media) i then dragged the entire contents of the 'my music' folder onto the ipod.
Repeated the same process on my laptop by dragging the media to the required destination and then deleting the folder from my ipod.
An ipod is, afterall, a massive USB storage device. I regulalry use it to get music....err....legitimatly....from my mates pc to my own.