If speed is a disease, Vista is the cure
Vista is rubbish. It's bloated, fat code with delibrately-designed-to-annoy features such as UAC, and far too many memory-hogging, value-taking features. Too many shadows, animations, high redraw rates, Aero, the appalling Windows Flip 3D, : too much eye candy, not enough function.
Vista out of the box is designed to please an ADHD child who is impressed with whizzy graphics, and not someone who wants to get the job done with a minimum of fuss, quickly. It's a toy, not a tool.
This sounds similar to my experiences. My Acer was crippingly slow until I paged the VM off the HD to 2GB + 1GB Memory. However, when my hard drive fills up, I have to do a spring clean. It took me hours to dial back all the Vista settings from 'whizzy' to 'fast', switch off all the animations and redraw ratios, so it looks like XP on a Vista chassis. Being a propellorhead is ace. Even my 512MB XP goes like a caffeine-crazed Ramones compared to the 1GB Vista.
(The laptop was a preinstalled present, before you ask.)
Aside from IE browsing, I'm happy with a Windows 3.11 platform actually. I don't do much with Vista but Thunderbird, OpenOffice, iTunes (now that is crippingly slow), and Firefox.
What Redmond have missed is that I'd much rather have something go fast than something be flash. I couldn't give a fig about a glass-interface : I want it to open a menu bar or document when I click on it, and FAST. Speed is a function in itself.