If you can find a good machine that is from a company that makes good drivers (and has hardware partners that are making nice behaving drivers), then you will have a good experience with Windows Vista. That's why I'm enjoying 64 bit Vista on my Lenovo T61p including the fully accessible 4GB of RAM (best install experience that I've ever enjoyed too).
I like Vista - even if I wasn't a MSFT employee. There are many stereotypical arguments about Vista - it's expensive, what are the compelling features, it needs new hardware, it's slow, etc. Yes, while it works better with newer hardware (and good drivers written for Vista), most of these arguments are not well founded (i.e. FUD). Inside, Vista is a radical rewrite and has serious architectural changes. This is well documented stuff, so I won't go into my soapbox on that. So, let me point out that there are a bunch of nice utilities and features on this machine. We had PerfMon back in Windows XP and earlier days, but I like the new Reliability and Performance Monitor utility better. It gives a lot better insight as to what processes are stealing time.
Below I've included a screenshot of this monitor running on my machine. In this case, I'm looking at the default view. You can see that there are other options to drill into - including our old friend, PerfMon. This new tool has a nice look across the factors that impact performance (CPU, Disk, Network, and Memory), and the corresponding detail windows are more informative than PerfMon's.
Another reason to like this utility is the Reliability Monitor (seen below). This is a graphical view into a database of machine issues. By clicking on a day, I am shown what was installed that day (included Windows Update), application failures, O/S failures, and miscellaneous errors. Very nice indeed.
I'm just scratching the surface on this, but I get what I need from these screens. So, see, another good reason for Windows Vista.