After my comments about Google Desktop previously, I decided to have a look at the website for it, and it shows as supporting Vista, so I decided to give it a try again. Google now seem to have resolved the issues I had with it previously, and it's working fine now. Unfortunately, I have to run it alongside Yahoo! Widgets as I need that for the Last.FM BBC Radio application.
But it's a great tool. The widget sidebar is good, far better than the Microsoft one that is installed by default, and probably a bit better than the Yahoo one. As well, the quick search box is incredibly useful. You can use it as an application launcher, which is great - I've gotten used to using Katapult to launch things in Kubuntu, and this makes an excellent replacement for this. I'm so enamoured of it I decided to install the Linux version on my Kubuntu laptop as well.
Unfortunately, this version lacks the widgets, and I still prefer to use Katapult as a launcher. But it's still useful. The default key for starting the Quick Search box is Ctrl-Ctrl, but I've changed it in Kubuntu to the Windows key - after all, I'm not going to use that for anything else, am I!