So green = home (don't think there was a "Windows 2000 Home", as it was the NT of Me's era), and blue = professional. What does black mean? It's not like there was a "Windows 2000 Ultimate", or whichever of the 32 flavors of Vista black is.
Shinjidude, cheese: Her motto ้ ผใใๅฅณใงใใใ is "I'm a reliable woman", not "I'm reliable because I'm a woman", that would be something like ๅฅณใฎใง้ ผใใใงใใ That ใงใใใ at the end is semi-idiomatic, it strengthens the point in a polite way, and implies that you can indeed trust her because she's reliable.
The question remains, which one is black? I don't think Windows had anything but the Green=Home, Blue=Pro color scheme until Vista. And the Green=Home didn't start until Me came out.
my gigantic os guide image says that because nobody cared about ME's versions people only bothered to use one color, XP home had the color variations. Also that 2k didn't have standard color variations for the different versions.
Ok, I remember there being more green on Me's box than there was although the Windows logo is boxed in green. 2000's box is completely not what I remembered. I think the characters' hair colors coupled with XP's color scheme are forcing me to retcon the old box designs in my mind. Me was a home OS, and Me-tan's hair is green. Windows 2000 was a professional OS and 2k-tan's hair is blue.
In any case, I agree with Log, that someone just felt like coloring the wallpaper the way they liked. In this case a more naturalistic color scheme.