I tryed the Windows Vista Ultimate on the 10 years old PC I have and it works like charm,including playing the games.Here are the PC specifications:
-512 MB of RAM DDR1
-1.6 ghz
-512 KB cache
-Graphic card 64 MB and 400 mhz
-HDD 34 GB capacity (I know its small but back then it was big

)
As for the Windows Vista Ultimate operating system,I have done only the most basic changes:
-Aero was turned off automatically of course

-Then I installed SP1,restarted computer and then installed SP2 and then restarted computer again
-I increased the virtual RAM on 4096 MB (it was the 32-bit edition of course

)
-Then I decreased the quality settings on the minimum in the graphic driver options
-And so on...
In any case you do NOT need strong computer to run Windows Vista (any 32-bit edition) at normal speed...including games.:good:
Same for the Windows 7 (any 32-bit edition).I tryed them too.
As for the 64-bit editions of the Windows Vista AND Windows 7,I haven't tryed them yet on my super-old PC,but I am pretty sure that it would work very slow or it wouldn't work at all.