WinNT, K6, nVidia: yes, if you are lucky you can get things running on them, but the odds are higher that you will have troubles of some kind.
OSR2, Thunderbird/Pentium, 3dfx: you can be sure it is going to work.
As for Whistler, yes MS has been trying to force all the consumers onto the NT kernel for a long time, and once again they are saying that they are going to do it. Maybe they will end up releasing another 9x OS though. Then again, ME is worthless, so perhaps there is no point to looking forward to a successor to ME. I am confident that OSR2 will continue to run stuff just fine for the foreseeable future. My hope is that, say, three years from now Linux or something be a major alternative on the desktop, with as many games for it as Windows has.
Until then, I am clutching my OSR2 with my clenched lil fingers.
And I'm not buying an nVidia card until the 3dfx engineers have put all the good stuff into it.
Dufusyte (rebel)