[Coda]

If you compare Vista to XP, you'll understand. Vista is much slower than XP, requires a much more powerful system to run, and (especially 64-bit Vista) doesn't support as much hardware as XP. The default settings are also very annoying; its security stuff is both annoying and counterproductive (if it prompts you for EVERYTHING you stop paying attention to it, so you'll let through something that should have been denied).

If you compare Vista to 7, you probably won't notice that big of a difference. They're essentially the same operating system -- Win7 is actually 6.1 (Vista is 6.0) if you ask the OS to identify itself. Win7 has a lot less annoying defaults and cleans up some of the performance issues of Vista, but XP is still faster and more compatible.