Actually, the big kicker isn't the machines that can't run Vista with all the bells and whistles, but those that cannot even run basic. If it isn't in that lawsuit, it should be.
You see, the problem came in, NOT when those trying to run ultimate couldn't, but when many of the general populace started getting computers from Dell, HP, and Toshiba with two factors that made Vista Basic run terribly. The processors weren't good enough, and the RAM at the minimums made it so that it ran very sluggishly. People began to complain that their machines weren't running that well, and on top of that couldn't run a majority of the programs in Vista. That aided to a snowball effect that rapidly engulfed those with higher forms of Vista.
So you see, at it's core, the issue isn't about Vista with all the bells and whistles, but whether a computer can run Vista period. I think people have individually talked about similar lawsuits against Dell, and HP, but who knows. Dell now offers computers with WinXP (actually happened that they switched rapidly after Vista's release with the reasoning of allowing people choice and increasing options, but with the outcry before that one sometimes might wonder) so that would probably become a null lawsuit rapidly...however one against Microsoft...
If they include that even Basic wouldn't really run on many of the computers so advertised...I think it is at least admissable in court to hear both sides of the story and see what a judge thinks about it.