Ah, you are so faithful... Actually, Vista failed especially when it became popular and available for for machines that had extra memory and processor speed.
That is when it showed its problems because many more uses were upgrading as the hardware became available, but I am sure you disagree.
Vista was never viable for the masses and was proven so by the rapid development of the next OS to fix the problems (by Microsoft). To support Vista, you have to have to loved the earlier OS that had major problems.
Really, do you think the problem with Vista is not enough advanced systems available out there in the world of gamers, enthusiasts, etc. that it just did not get a good test? Geez!
Sorry, but the gamers alone would and did tell the problems with that OS!
But due to those complaints, when Microsoft developed Windows 7, they cleaned up a lot of the operating system code so even with 2 GB of RAM, it could still run in 64-bit memory addressing mode if your CPU supported x86-64 instructions. In many ways, Windows 7 is essentially the fixed version of Windows Vista.