We upgraded one of our machines to Vista this weekend (click, wait several hours / pack several boxes while waiting) and it does indeed look gorgeous. Thing is, though, the box we installed it on is a small form factor machine - Shuttle box size, with a beefy graphics card to make it possible to have pretty glassy windows. It's an Intel box with a 3GHz proc, 512Mb RAM (yeah, not enough, I know)*, a plentiful hard drive, and a Radeon 9800 Pro graphics card. Vista will run, but as predicted, the extra demands on the system are causing the normally silent box to run with its fan on fairly noisily because all the components are running at a higher temperature. It's getting hot in here!
The 3D demands of this lovely looking beast are causing the graphics card to actually have to do some work, which is what we expected. The worry with a small box is that you have a lot more difficulty keeping them cool than with a normal tower chassis, so we recently replaced the processor fan with a much higher quality fan to help keep it cool. The most demanding application of all that we've found so far is the screensaver - far better to have a blank screen and use power saving options like turning off the monitor and hard drive.
One noticable side-effect from being at home with Nathan has been the increase in the electricity bills here, so I'm making much more of an effort to turn off machines not in use, using hibernation, and generally turning off anything not required. I'm just wondering how much my bill will go up from having a machine running hot all day instead of just warm - it would be great to have a side-by-side comparison of power consumption between two identical machines, one running XP, one running Vista. With global warming becoming more of an issue than ever, it's slightly worrying that a significant proportion of the world's computer users will be migrating to Vista or buying new machines that run Vista - I can't help but wonder what even a 1 watt increase in power consumption per computer could do to the environment. The "turn off your TV, don't use standby" campaign is rallying against people wasting a few watts of power - yes, every little helps, but surely it makes more sense to get people to make a bigger difference by turning off lights that are left on unnecessarily, washing at lower temperatures, boiling the kettle more efficiently, etc. I'm guessing that most people will not notice / be aware of any difference to the amount of power their PCs are consuming just because of new software. On our gaming machine here, the Asus motherboard has some great monitoring tools, and the difference between idling on the XP desktop (CPU usually around 32 degrees Celcius) and running a graphics intensive game (Half Life 2 or Sims 2 can get the temperature up to 55 degrees) is huge. We've not installed Vista on that machine yet, so I can't compare idle temperatures yet (I want to make absolutely sure I can still play my games first!) but when I do eventually upgrade, I'll probably post information on the differences. From current experience, though, Vista is a lot more like running a game continuously than leaving a simple Windows XP desktop in view.
* UPDATED 29th Nov 2006: Installed an extra 512Mb RAM yesterday and Vista now runs very smoothly. The overheating problem remains, but at least I can switch applications with ease - previously, I would click and wait while the hard drive churned through the 1.5Gb virtual memory mountain! I'd highly recommend anyone who gets Vista has at least 1Gb RAM.