LarryOsterman wrote: Embedded isn't a consumer SKU, it doesn't count. I think that there's only 6 SKUs currently (I may be wrong).
And if you count "Professional x64" as just "Professional" (since they both have the same feature sets (spare the x64 support) then you're back on 5.
There are two you haven't counted in yet: Windows XP Professional N and Windows XP Home N. These are the SKUs required by EC in Europe. N=No WMP or something like that.
However I do see Pro and Pro x64 as two different SKUs