Atheros WiFi cards are generally well supported out of the box by all GNU/Linux distros. There's some others but I don't know them.
I used few models of asus eeepc (700 and 1005PE) with SliTaz and it works well. Some tweaks are needed to have the 16/9 display with the intel graphic card and Xorg. The other hardware works well. I don't know about cam : not tested, but should works.
I think that most of the laptop/netbooks should works well with SliTaz, the most important thing to check when you want to use them with GNU/Linux is the WiFi card. I saw some issues with toshiba laptop (fan doesn't works as expected, laptop shutdown when the CPU get too hot), so my advice is to don't choose them, because I don't know if it's fixed now.
A last thing : don't choose too recent hardware, because there's often a delay between hardware product, hardware support in GNU/Linux and package update in Linux distros; specialy if you want to use SliTaz stable. I.E. : with eeepc 1005PE only SliTaz cooking works well because the WiFi atheros card is too recent to be supported by the Linux kernel in stable without recompiling it with patches.
A year or two should be fine I would imagine. I've used a bunch of Dell laptops, Inspirons, Latitudes, Vostros, and they seem to mostly work fine. Recently setup an old Compaq Presario and that seemed to work fine right from the start (note none of the above except the Dell Inspiron comes as a netbook, not that it makes a difference).
My Dell Mini 9 Netbook works great on Slitaz, although i wouldn't really recommend it to anyone since the keyboard is unusably small. I hear the Mini 10 has a regular sized keyboard. The Mini 9 also has a built-in cam, and that worked fine as well, as does the Bluetooth module, mic, speakers, what have you.
I would buy a Toshiba AC100 - it has g/b/n, is very light, has a good screen, great build quality and is with the dualcore Cortex A9 and the Nvidia GPU more powerful than most of the Atom CPUs, plays HDMI, but is not supported now by SliTaz. So here my question to the dev team - how far is the arm port of Slitaz?
Android is not the best Os for it - until now there is running Ubuntu and Gentoo on it, but slitaz would be much better.
and if you really want a Netbook with Poulsbo Grafic I suggest you to find a Dell Mini12: the Asus Eee PC 1015PE has a bad display and is quite loud - Dell Mini 12 - it has a Z530, a better screen and no fan, but no N
if you really want the cheapest - choose one of these
but generally I prefer used Buisness Notebooks from ebay normally under 200€, you either change the interneal MiniPCI Wireless card or us a PCMCIA Card for wireless N
My faforites are: Toshiba R100 works very well with SliTaz (I use 3 of them in work) IBM X31 works very well well - I use one Dell Latitude D420 HP NC2400 IBM X61s (a bit more expensive - about 350€ now)