My first usage of Pro/ENGINEER was on a PC using Windows NT 3.5 five years ago. The setup has horrible. The problem was Windows; it constantly crashed and locked up. Shortly thereafter I was using an SGI RS10000 OCTANE. This setup was bullet proof, but that is what you get with UNIX. This year I switched all of our CAD engines that I could to a Windows 2000 Professional. The reason I did this was because it was by far the most bang for the buck. If I could have had the money UNIX would have been temping, but I would not have the speed that I have. Until this year when I began using Windows 2000 I would have never advised anyone to use anything but UNIX for Pro/ENGINEER or any other large CAD engines. My complete setup is using Windows 2000 Professional on a Dell 600 with and IBM server running Windows 2000 Server. I have had minor issues with Windows, but when I consider a few faults for the investment and processing speed, I can not complain. Window2 2000 is the first MS operating system I have trusted. I still have a license of Pro/ENGINEER on an IBM running Windows NT 4.0 that is getting switched to Windows 2000. There is a big difference in stability between Windows NT 4.0 and Windows 2000 Professional. You have to look at everything thing you are using, but on the basis on of just running Pro/ENGINEER I have no reservation about recommending Windows 2000 Professional. I also run UG V16 and I-deas 9.0 on the same Dell workstation. The Dell I use has 1 GIG RAM and a P3 1000Hz Xeon. It is 3.3 times faster than the RS10000 OCTANE. I use Pro/ENGINEER, UG, I-deas and a little CATIA. I believe that Pro/ENGINEER rules; UG is nice and I-deas is an absolute waste of money.