If I purchase a Mac Mini, will I notice a significant speed change?

[spinnerlys]

This simply isn't true. Windows 7 (and Vista for the most part) feels much snappier and quick than OSX. Try managing files in Explorer vs Finder. Try switching apps in Win7 64 vs Snow Leopard on the same machine.

Windows feels faster without question. Just try it, instead of assuming Apple is better here.

I should have specified Windows 95 to Windows Vista I assume.
The three instances I used Windows 6.1 (called Seven for marketing purposes), twice the beta version (RTM?) and once the final version, I kept deleting it due to a misunderstanding between me and the OS. We where not meant for each other. I was to simple for it.
Really, I got cramps and got angry of how to use it. It was nothing like Windows XP, the last Windows version I used heavily, which might not be a bad thing, it was just illogical for my train of thoughts.

So therefore I assume, and as the saying goes, IMHO, that Mac OS X feels more comfortable to use, better to navigate, not in a sense of snappines, but more logical and more profoundly un-confusing, and much better thought out.
And what's standing visually out, not as appalling as Windows 6.1. The colours are just abysmal, not really easy on the eye. I have seen Linux versions which looked better. But I don't want to turn this into a Windows versus Mac OS X debate, so I cut it here.

And to repeat the much quoted saying, which was absent from the post you quoted, IMHO.

 

[miscend]

The speed change will only be in navigating and working with the OS, therefore it could be perceived faster.
But mathematically the Mac Mini is slower.
Only OS X's GUI and underlying components and philosophy will make working with it seem faster than with a Windows PC. But that also depends on your habits and maybe OS X does nothing for you.

Agreed. Otherwise you're getting a CPU downgrade in the Mini.