According to this document, Sony took the easiest route, merely providing the Green Dam program on the hard drive, listing its location in this document, along with a number of disclaimers, such as:
"Sony cannot guarantee the authenticity, legality, or compatibility of the software's content, function, service or any other feature."
"Sony assumes no responsibility whatsoever for any kinds of loss or harm incurred by the user as a result of use of Green Dam. Sole responsibility lies with the software's maker."
The document also says that Green Dam doesn't support a 64-bit operating system, and will therefore not be shipped with PCs that come with a 64-bit OS. Once again, this shows the sloppiness of Chinese censors and the haste with which this measure was undertaken. Requiring all manufacturers to ship a program with all their PCs, but not providing a 64-bit version of the program? I wonder what kind of security holes it contains.