I've been running Windows 7 for a while now. For the most part I have been rather happy with it. It feels much more stable than Vista does, and more "shiny" than XP. I had a reason to look at a Windows 2000 PC at work and ... it was a bit frightening, we'd rather not go quite so spartan.
I ran this laptop for the last two months on Windows 7 and felt it was a bit sluggish but knew that I had the low end spec of this operating system. This is an older Acer machine with 2GB of memory, a Core Duo (not Core 2 Duo), and a recently upgraded 500GB 7200 drive. The faster hard drive gave me a performance boost, but it still felt lacking.
I caught a memory sale at www.Newegg.com for exactly the memory I needed to bring this up to its maximum. This PC won't run the 64 bit version of Windows 7, so I top out at 3GB. This isn't a fault of Microsoft, and they warned us that any windows 32 bit version will only take 3GB. That's the same with Linux, and I have to assume that it will be the same with Mac OSX.
Tonight I got my memory and I noticed the difference immediately. I work on the blog on Firefox, and I run it within a virtual version of Windows XP and if the host operating system was sluggish, the virtual version was like running through mud. Now everything is faster and snappier and I'm sure while that will fade, everything is much easier to use.
So, Class, if you're running Windows 7, get yourself up to 3GB. If you're have Windows 7 64 Bit, I've got 4GB at work and it runs fine, but I have heard you want 8GB.