First, some history -
There were, at one point, a few distinct branches in the Windows evolutionary tree. There was the 9x branch (95, 98, Me), which was not really connected to the NT branch (NT, 2000, XP, Vista). Generally speaking, the 9x branch was fraught with deep architectural problems and it was ultimately discontinued for this reason. So I agree that Me is the worst version ever released, given that it was only a very slight update of 98 released in 2000 (the year, that is).
I think it's a little difficult to compare the stability of the NT branch to the 9x branch, because in a sense it's apples and oranges. It's possible (even common) for a very basic user application to hang an entire 9x system, and this problem just does not exist on NT.
But that being said, I think the NT kernel has improved overall with each release, so I think XP performs better and is more stable than 2000. What may very well be less stable is the specific set of device drivers for the hardware that you currently own if you run XP. Kernel bugs are far from impossible, but the majority of blue screens will be caused by drivers (and I suppose malware).
How's that for an answer!