As for what it is, basically its just someones composition of programs added to an unattended install.
Its called XP black because it feature the above xp theme…
As for rootkits, spyware, etc. Already scanned and nothing. Its pretty legit. Also it already had the bypass installed so it gets past the Microsoft upgrade check.
And yeah nlite is an easy way to make an unattended install, there are tons of ways to do that. I remember at college we had to do I think 3 or 4 different unattended for 98,2k,2k3 server, and XP. Ahh the fun days