yes, that's what we meant, but you seem to be confused about relation between drivers and OS, but that's another story...
yes, vista is fundamentally different, it was a stepping stone to win7. Another very big difference is win7 was written to be a 64-bit system, while XP is a 32-bit system by design.
drivers are just drivers, it's instructions that let the computer instruct a piece of hardware on how and what to do. There's no OS requirement for driver installation, because it is just a set of instructions. You can install win7 drivers on xp right now, they won't work, but it doesn't mean it cannot be done. Same with vista and same with win7. You install drivers that will work with your current OS, it has no relation to other OS you might have possibly used in the past or will use in the future.
and I'm not sure what you mean by baggage... when you install win7 you will reformat the hard drive...