I have an MSI Wind netbook with 1 Gb RAM running XP. I've also loaded a Linux distro called Jolicloud. Both run well and whilst it isn't as fast as my i3 dual core laptop with 4 Gb of RAM it's fast enough for portable use. It's not a replacement for a laptop and if you want the performance of a laptop then buy a laptop. However I'd not replace my netbook whilst travelling and it has the massive advantage over Tablets of a complete QWERTY keyboard that is very usable. It also has 3 USB, Card Reader, LAN port and VGA port (which displays at 1920*1080 on my monitor).
If I run Jolicloud (a genuine 'cloud' OS) then it becomes very fast and has a massive battery life in 'sleep' mode (96 hours with a 7.8 Ah battery). It runs for about 7 hours on the battery using WiFi.
So it's horses for courses.