One of Linux's strengths use to be support for older hardware - but Unity struggles and Gnome 3 refuses to work on my IBM T23 Thinkpad.
XFCE is barely bearable after Gnome 2, LXDE is almost impossible to configure, and KDE is so slow and klunky it's not even funny - for a Fedora user 'fings ain't what they used to be'.
David
PS Fallback mode? - Don't get me started!