I'm afraid i can't provide lots of technical info because of my little use of NT, but from what I've learned, NT 4.0 still goes more or less strong because of 3 rules: 1) If it's not broken, don't fix it 2) If it's newer, it'll cost more 3) If you change something, you can never be 100% sure what will happen. In other words, NT 4.0 is tested many times, and many an admin has gained skills and experience using it, and know the tricks of their trade. Also, if a piece of hardware, let's say a aerver machine in a small business is known to work well with 4.0, many admins rather use that than install newer os's, because you can never be sure if compatibility errors and whatnot occur. This I have gathered from here and there, mostly from old and newer admins, please remember I'm just a student so if i'm horribly wrong, don't execute me. As for myself, I installed win 2k3 server on my old pentium 3- based hardware, and it has no problems working at all, even a (very small, mind you) MySQL database worked on it smoothly, and it does not have a lot of memory. Also, it's a nice treat to have Active directory in-built in the os. Hope I helped at least a little bit.