It's more involved than doing it on Ubuntu. To be honest the hardest thing you're likely to do is getting X running, closely followed by picking a window manager. Sound and Wifi are generally straightforward on Arch.
To put it in perspective, I use Arch on a P3-850-based Sony Vaio with 128mb of Ram and it flies.
The main things you'll get from Arch on a netbook are:
* Rolling release means that you don't have to do distribution upgrades.
* Have it your way - you pick what you want, what window manager you want, what editor you want etc. Use something like AwesomeWM, Xmonad or OpenBox to get the most out of your screen real-estate.
* Efficiency - Because you're only running what you want to run, your memory usage will be better and you wont have things you don't need lying around your hard disk, leaving the space to be filled with things you do.
The downsides:
* It's not a mainstream distro. While it has a great community, it's not as ubiquitous as something like Ubuntu. Still, Arch hasn't yet had it's eternal september so the people you do encounter know what they're talking about.
* You will tinker more and it will take up your time - if you don't play around then everything should work fine, but with the amount of flexibility Arch offers you will inevitably go through Window Managers and various tools, at the risk of breaking something.
> Rolling release means that you don't have to do distribution upgrades.
This goes beyond the OP's question. How does arch handle changes in essential components like the switch to upstart in ubuntu? Does this work well with rolling releases?
I've been an Arch user for ~1 year (Gentoo before that), and "essential component" upgrades seem to take place just fine. For example, there was a recent shift from Python 2 to Python 3 as the primary Python interpreter, and there were no noticeable problems.
I'm sure it varies by system and the specific hardware, but I don't think it was too bad when I did it and I'm hardly a Linux expert (I've been using Arch for a few months). There will probably be a couple hurdles as you'd expect from a fairly custom Linux install, but the extensive wiki and large community make it relatively quick and painless to figure out what's going on and how to fix it.
That said, if you're looking for something as quick and easy as possible you might want to look around a bit more to see if there are any prepackaged systems that do exactly what you want with less setup. No sense making this more complicated than it needs to be if something else comes up that closely fits your needs and could potentially save a couple hours of troubleshooting.
