blotunga: Windows 2000 was actually pretty good compared to NT4 but XP came along pretty quickly. Also it was aimed for business customers only.
I think it was mainly for business use, but it was quite good for home use too. As far as I could tell, it run all the games that XP did, I think it even supported all the same DirectX versions as XP, and it also offered similar "compatibility modes" to get e.g. old Win9x games to run on it, like XP did too.
The only problems I found for Win2000 for e.g. gaming use was that e.g. ATI graphics drivers for Win2000 were lagging a bit behind XP drivers, but they were still in a good level.
Another blow was when Valve suddenly stopped supporting Windows 2000 with Steam, meaning that all the Steam games I had bought for Windows 2000, suddenly ceased to run (just because the Steam client suddenly refused to even start on Windows 2000). That was my major wake-up call how these forced DRM clients suck and prevent me from playing games I've paid good money for on my PC. A bit like my old PS2 games would suddenly refuse to run on my genuine PS2 console, just because Sony suddenly decided so.
Overall though, XP did indeed make Windows 2000 obsolete (at least for home/office users), but Windows 2000 to me felt like a polished, early version of XP, with most of the benefits that XP offered over e.g. Windows 9x series (like NTFS and so on). And it was definitely better for Windows (also 9x) gaming than e.g. NT4 and such.
Maighstir: Keep your 7 license (sell the box with only 8 on it) and install it side-by-side with 9 on the new machine?
Can it be reused like that, by just removing it from the earlier PC? Windows 7 was preloaded on that PC (OEM?), so I always presumed it is tied (at least from a legal point of view, not sure if also technically) to that PC and that's it.
I later bought the cheap Windows 8 Pro upgrade on top of it, and it allowed me to install Windows 7 and 8 Pro side by side (and later 8 was upgraded to 8.1). Come to think of it, since the 8 was an upgrade license from 7, that probably complicates things further, ie. maybe I am not supposed to leave Windows 8 on that older PC either, in case I transfer the Windows 7 license to some other PC?
And frankly, since I was thinking of buying yet another ASUS machine, at least ASUS seems to have this habit of optimizing their newest PCs to the newest (current) Windows versions. E.g. I think many people who had Windows 8 preloaded on their ASUS machine, had major issues downgrading it to Windows 7. Just what I read though, don't know the specifics.