I got my new Alienware computer 3 days ago, and I can't remember the last time when getting a new computer was such a struggle. Part of the problem is a known crash bug with Nvidia nForce 680i SLI motherboards and SATA disk drives. For some reason I can't get Nvidia's hotfix for that to run, need to wait for Alienware to provide me with a BIOS update. But apart from the rare random blue screen of death, the main problem with the new computer was Windows Vista.
The computer came with one user account with admin rights, and at first I didn't create anything else. That turned out not to work well, I got constant "security options dialog" error messages. Some research with Google suggested that this happens because Vista is trying to kick up some security requests to the next higher level of account, and if you are at the highest level, you get that sort of error message. Not sure if I understood that right, but I created a second account, a simple user account without admin rights, and running on that this sort of error message disappeared. What didn't disappear was Windows Vista's annoying habit to doubt everything I did. You start a program, any .exe, and Vista tells you that running programs on a computer is a potential security risk, and asks you to confirm whether you are really, really sure you want to do that. That drives you up the wall pretty quickly.
The one program that ran well under Vista was World of Warcraft, which is because WoW puts all its data in the same directory, and doesn't use other directories or the registry for anything. I had less luck with other programs. The Lord of the Rings Online beta client I couldn't get running at all, because it works with several different directories, having parts of the information in your Documents folder. And again Vista's security features kicked in, and didn't want to let LotRO have access to the Documents folder. Apparently there is some way to assign rights and exceptions so that programs can actually use data from folders, but it is damn complicated.
In any case, after 2 days of working with it I still couldn't see what the advantage of Vista should be. It worked exactly like XP under a new coat of paint, and with lots of annoying security features that prevent you from working with your own computer. It was often annoyingly slow, even on this new high-end computer. And there was no good documentation to navigate around all the pitfalls that Vista still had. So yesterday I just gave up on Vista. Reformatted the hard drive and installed Windows XP. A friendly Alienware technician told me that the mainboard SATA crash bug might be less frequent if I put the SATA cable in another SATA port on the motherboard. I did that, and didn't have a crash since. And under Windows XP I don't get any other error messages either, and a lot less security warnings. Even LotRO was running without problems.
Finally I was even able to run 3DMark05, which doesn't run under Vista, and compare the speed of my new computer to the previous one. Not bad, a 3DMark05 score of 13,928 is more than twice as high as my last desktop from 2 years ago.
Vista only caused me trouble. But hey, it was an experiment. I knew I could always go back to XP. I can't recommend Windows Vista for gaming at the moment. Maybe in a few years, when the game developers have programmed their games to take account of Vista's security standards. But for the moment I'll stick to Windows XP.