The release of WIN2000 that's about to happen is intended for mainly commercial users, as to all intents and purposes, it's NT5 under a different name. There's 3 levels, and the lowest level is the equivalent of NT workstation. There are for sure issues about backward compatibility for some programs, especially things like games that use low level access to the hardware, so be careful.
There is supposed to be a WIN98 upgrade to the same sort of spec as WIN 2000 in the pipeline, but as far as I know, it's some way out yet.
In a nutshell, if you're using a home machine, and not running a lot of heavy business applications, WIN2000 may well not be the right next move for you.
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"Irish" Steve