With some extra time, I managed to take a test drive of Microsoft Windows 7.  Here are the results.

You are not going to believe this.  I just loaded windows 7 ultimate on an older system.

The system hardware configuration is:
Intel Pentium 3
Nvidia 64mb  mb vga card
768 mb ram memory
20 gb drive

Windows 7 says it is an evaluation copy but so far it works.  It used 11 gb out of 17 formatted.
It complained a bit about the 768 mb during the install saying that it wan't 1 gb but it loaded none the less.
It did not find the network card which is fairly new and the sound system which is on the mobo.
Awe darn, the screen saver says that it can't work without a newer direct3d card.
Ahhhh but it will let me install a few gadgets on the screen that managed to do 1024 resolution.

Internet won't work even though I got it to recognize net card.  It won't get the correct dns from the router.

So there we have it, Microsoft claims that Windows 7 will run on older hardware and it does.