I have had various version of linux running on *very* old hardware, that is still running. In fact, my server is a 900MHz Athlon with a TNT2 video card, it works months on end doing all kinds of work and never a hiccup. So, I think you need to re-look the whole "older hardware" statement.
1. Resource management - Windows (all versions) are resource hogs. Most notoriously, Vista requires some pretty steep hardware requirements ***JUST TO RUN THE OS*** (was that loud enough for you?). But, XP has terrible memory management as well. Anyone that folds can verify this simple fact.
2. Freedom - Both as free of cost/maintenance and freedom to change/tweak. MS has a horrible setup that does more to restrict the user with every iteration. I like to be in ***control*** of my system, not the other way around.
3. Networking - Linux/UNIX's networking stack is superior, period. Plus, just as a pet peeve, Windows doesn't even offer SSH as an option.
4. Software - I can get all of the software (management) I need for everything I need to do (except newer games), from one source. And, its usually free.
5. I have a lot better security in Linux. Mostly because I setup my router/server/firewall and wireless router/AP using linux, but also the host systems are better secured to intrusion or compromise.
But, I've only been running linux for 11 years...what do I know?
I am a fellow linux user like you...
Micro$atan releases these new monstrosities on us every few years...and force us to upgrade our hardware and or computers. But do we NEED to upgrade that much?
Heck I just got Vista to install on a older Hewlett Packard Pavilion 7340 (Pentium III we're talking here) with 512 mb of memory ...and a 256 mb Nvidia card.
it runs a teensy bit slow...expected from a computer with a 1 gig proc and 66(?) mhz FSB I suppose.
To differ with what someone else said about hardware support...newer linux distros that are being released have better and better hardware support..ESPECIALLY for older computers.
Mepis has a variant called AntiX (pronounced almost like 'antiques') which runs comfortably on a old computer I have here at the house with a 233 mhz proc and 256 megabytes of memory and a 32 mb video card.