So someone just asked in #kde4-devel whether it was worth trying KDE 4 on a 2500Mhz/256Mb computer and I was characteristically careful and guessed "It will work, but won't be good.". Then I decided to put my money where my mouth is and booted my Thinkpad X60 with "mem=256M maxcpus=1", logged into KDE 4 and set the power saving policy to "Powersave", which throttles the CPU to 1Ghz and locks it there. [...] And I was pleasantly surprised with how well it all works.