The Self-Modifying EULA?

An anonymous reader asks: "Years ago, when I first installed Windows 2000, I accepted its EULA. Despite serious defects in the product, I resisted installing Service Packs because they modify the original EULA. Now even Homeland Security is on my back to upgrade and install a fix. I would be happy to install SP4 and all the security patches BUT ONLY IF IT IS DONE UNDER THE ORIGINAL EULA. Otherwise, Microsoft has made me an unwilling zombie. The clear fact is that Microsoft delivered a defective product- should not allow them to redefine our agreement. I cannot think of any other market that successfully browbeats its customers in this manner. Can this be legal? Has it been tested in court?"