For Windows computers external to the physics local network, you need to get some ssh/scp program. Fortunately, this is easy when you know where to look.
There is a free ssh (and scp) program from the physics web site (internal access only). A publically accessible download location is here. This program has a very nice GUI interface. However you need to have installation rights on the Windows computer to install and use it.
For other cases, PuTTy comes in very handy. There is a program for an ssh terminal (PuTTY), and an scp program (pscp). The pscp program is particularly elegant, since it doesn't even need to be "installed" on the Windows computer. Just put pscp.exe in the directory to/from which you want to transfer files, then open a terminal window (usually under Accessories), cd to the directory (something like CD C:\Users\Bob), and use pscp like you would use scp at the command line on physics. See the section on scp.
Yet another option is Knoppix, which is described in the next section...
There's a fantastic Linux distro called Knoppix. It's a complete Linux system on a CD. You stick the CD in any PC with a CD drive, boot it up, and you have a functioning Linux system with much useful software, like Mozilla, OpenOffice and SSH. It does a fantastic job of hardware detection, and you can mount the hard disks if you need to read/write to them. It's also easy to establish a network connection. In fact if there's a Windows installation on the computer, it will read the network configuration from the system files on the Windows partition. When finished with Knoppix, pop out the CD and reboot and the computer reverts to its former personality. I really recommend that you take a Knoppix CD with you when you travel. It makes it very easy to connect back to physics.