I use Vista at home, and XP pro at work, and I much prefer Vista.
I find it so much quicker to load and applications it seems much more responsive. Both systems have a similar spec, although the Vista machine is a laptop.
The key benefits to Vista (in my opinion) are:

* User Account Control – I run as a limited user until I need to escalate, just as on Linux and Mac OS 10.
* Improved boot time. Start-up processes are launched with a low priority. That means real player, QuickTime and all that other useless junk doesn’t stop you from opening your web browser quickly.
* Better driver support. I put in a TV Tuner (express card) and Vista went online and downloaded the drivers. It took 30 seconds. No thinking required. That’s how I like it.
* Better power management. Mobility centre and Presentation Mode are something I use all the time.
* More reliability of sleep and hibernation. XP would frequently fail to hibernate after the system had been running for a few weeks. Vista always works. No need to reboot unless required to do so by an update. Hibernate baby!
* Windows update is a program! Not an ActiveX control on a web page as in XP.
* Start-up time (again): A new API for services allows them to have a delayed start-up.
* Lower disk activity: A new API for low priority disk i/o operations makes it possible to run virus scans and defrags in the background without ever really noticing it.
* Quick start menu. To open Microsoft Word, I hit WinKey and type “word” then press enter.
* All my favourite software. MIRC, Team Fortress Classic, Flight Simulator, Visual Studio all work on Vista.
* Native support for wireless networks – Did you know XP just simulates them? No more randomly disappearing access points. Much more reliability.
* Oh and Native IP6 support.
* It looks cool :)

The obvious downsides are old hardware won’t always work, and some older software won’t work.
I used a Mac back in 2001 when OSX came out (yes, anyone who criticizes Vista, go and use Mac OS 10.0, 10.1 or even 10.2 – they were much, much worse). The transition was just as bad, although helped by a classic environment I still had to buy loads of software and hardware all over again. That’s the price Mac users had to pay, and now Windows users are doing the same.

If Delphi 7 ran on Vista then I would probably run Vista at work too, unfortunately I still occasionally need to use it.

I obviously respect your view, and I wouldn’t recommend anyone upgrades XP to Vista. If it’s working for you then keep it until you buy a new PC. However I think anyone (particularly home users) downgrading a new PC to XP is foolish.
(With businesses they may have a specific requirement or their IT department may only want to support one o/s – that’s fair enough).

Of Course as a Died in the Wool Stable XPPro User. I do often chuckle at my Vista Friends Constant hassle’s. I find the security of Vista is also it’s nemesis, as an experienced XP user, I have a high rated Antivirus, But Don’t like my eggs in one basket have a high end Firewall and Separate Trojan/Spyware stoppers, and have Popups and redirects turned off. I have never had a trojan, Virus, malware, get into comp in 3 years. Of course I use Guutman to overwrite history, temp, and cookie files, every day. A lot, You say, but the resource use in the background for all is between 9 and 18%, with a 33second boot to desktop, and a 3 second delay in opening url page.
I luv my Stable XP. Hoping windows 7 is better with only a 578 mil byte o/s……But I will bet there will be a gig of updates over the first year.

Some people like XP because it’s faster, VIsta because it’s more secure. In the end, I think Microsoft needs to make a more flexible OS that can run a lot of services for a smooth operating environment on high end machines, while still being able to strip itself down and run on lower end netbooks and notebooks. As it is, Windows VIsta, while maybe the better system, still boots and shuts down in a much longer time than XP.