I'm seeing too many people try to compare software with physical goods such as cars and toasters. There are numerous, irreconcilable differences between the two realms that make a direct comparison anything but straight forward. Furthermore, many of you seem to have some inflated view of what merchantability and suitability mean for physical goods.
For starters, physical goods warranties and liabilities have limits. If I buy a truck from Ford, GMC or Dodge, it will have a certain rating for load capacity and towing capacity. If I exceed those ratings and something bad happens, up to and including injury or loss of life, it's my fault. Other physical goods, such as toasters, also have limits as to what situations they will be designed and tested for. If I try to make french toast using a slot load toaster and something bad happens, up to and including injury or loss of life, it's my fault. In one case the manufacturer knows that somebody out there will try something that they know has a high likelihood of causing known failures (i.e. if you try to tow too heavy of a load with your truck you run the risk of overheating your brakes and causing an accident) and in the other case we have to come to terms with the fact that idiots will find a way to break shit no matter how many warning labels you put on it.
Now about those irreconcilable differences between software and hard goods. With hard goods, your warranty goes out the window the moment you modify it in any way that has not been approved by the manufacturer. That is completely reasonable because I can buy a car and drive it completely as is and it will serve its full intended purpose with out any 3rd party add-ons. The same with a toaster, I can buy a toaster and make toast without adding to or modifying the machine.
A modern computer system, however, is nearly worthless until you start adding to it. Let's, for the moment, ignore hardware failure as being beyond the scope of software warranty. If I buy a system where the only installed software is MS Windows (and I mean *only* software, no games, no office/productivity, no peripheral hardware beyond standard keyboard, mouse and monitor, etc.) then there's not a lot of ways for it to break at a software level. Now let's start adding things. If my video driver conflicts with my antivirus software, who is to blame? Both work at a level close to the hardware to do their jobs and both have been tested to work as intended with the target operating system. And as luck would have it, they were both released nearly simultaneously so there was no opportunity for either vendor to test against the other's current product.
If we want to get into more industrial or life or death situations where computers are used, let me just say that if you trust human life or millions of dollars of equipment to the flawless operation of general purpose hardware running a general purpose, multitasking operating system then you're an idiot. The engine management and safety systems in a modern car are controlled by purpose built electronics running custom built software. Automated production equipment generally uses PLC type systems that been thoroughly tested for tolerances and MTBF rates.
Really what are we hoping to accomplish with this legislation? Windows, MacOS and Linux are all very stable (Vista's Task Manager is reporting 240 hours for my current uptime) barring hardware failure (which is easy for the lay person to blame on the OS since the OS is what tells us something went wrong) or applications that don't play nice with each other. Applications that corrupt data usually don't make it out of testing in that state and when they do it's usually fixed quickly if the company that made it wants to continue to do business. Open source software is perpetually beta since it is developed by the community and simply made available to anyone who thinks that it might be useful.