I have copied the file "login.keychain" on my old computer, but when I attempt to place it in Home/Library/Keychains on my new computer, I get an error message saying something like "can't be done as the keychain is in use." I'm sure this is probably a pretty simple operation, although entirely too complicated for me. Any help would be most appreciated.
Try moving the old one onto the desktop, then moving the new one in, then restarting. Then you can delete the old one on the desktop.