A quick video which shows the boot speed on an AMD K6-2+ 550MHz, 768 MB RAM and SATA disk system for Windows XP and Ubuntu 10.04. Bot operating systems are “stock” with the latest updates installed and no special optimisation has been done.
As you can see, you are much better off using Windows XP on a K6 machine as the Linux distributions with GUI are terribly slow on this hardware.
It’s not only the boot process which is slow on Linux but also the whole OS GUI (Gnome in this case) which feels awfully slow to the point where it’s unusable; Windows XP on the other hand is quick and snappy!
So the common myth that Linux is faster than Windows on old hardware isn’t so true here…