I've just installed Arch on an old laptop. After connecting to a wireless network, everything works for usually under a minute, then the connection (to the access point) drops.
The wireless driver is ipw2200, and there are lots of bug reports about frequent disconnects with it. The usual advice is to turn off power management (which doesn't help) or to downgrade to version 3.0 (which I haven't figured out how to do).
What confuses me is that wireless works fine (out of the box) when using an Ubuntu (12.04) live CD. I don't know enough to find where the Arch and Ubuntu setups differ, so I was hoping to be walked through the process.
Other information whose relevance I can't judge:
The Arch install is without a desktop environment. I've tried using wifi-menu and wicd for network management, and the problem exists with both. In the wicd settings, the WPA supplicant driver is by default wext and none of the other options (nl80211, ralink_legacy) work, and neither backend (external, ioctl) helps.
The output of "lspci | grep Network" is:
06:05.0 Network controller: Intel Corporation PRO/Wireless 2200BG [Calexico2] Network Connection (rev 05)
The laptop is Fujitsu Siemens s7020. Kernel is 3.5.6, i686.
Some of the output of iwconfig (I'm typing this by hand, which is why I didn't paste all of it. I could if it'd be useful):
Mode:Managed, RTS thr:off, Fragment thr:off, Power Management:off, Link Quality=62/100, Rx invalid nwid:0, Rx invalid crypt:183, Rx invalid frag:0, Tx excessive retries:0, Invalid mist:2, Missed beacon:19