Another side-effect is the possability of lowered performance. Windows 2000 does not understand a HT enabled P4 is actually one CPU. Windows 2000 thinks it is two physical CPUs. This is okay if you are doing two different things that do not address the same CPU resources, say, encoding a video and surfing the Web. As soon as you start to perform two processes that require the same portion of the CPU your performance will drop. Since Windows 2000 thinks there are two physical CPUs, each with its own resources, it tries to send the doubled info to "both" CPUs. Of course, there is only one CPU and one virtual CPU that share the same resources. So now, Windows 2000 has just bogged down your system, by trying to do two things at once, that it can't do adequately. If you really want to take proper advantage of HT technology, get Windows XP.
\Dan