At my work and as a personal experience I swear Atheros is the worst brand for wireless cards. We have been actively swapping out any laptops the company owns with Intel ones and that seems to resolve the issue. What I love is when people bring personal machines in and get angry when they can't connect and of course they have an Atheros card! Anyone else have issues with this brand?
There are a number of issues with any chipset that isn't Intel, though Intel had some issues at times with various chipsets themselves.
Atheros depends on the quality of the card's construction, not just the chipset, and there are plenty of cheap, crappy vendors. Broadcomm has its issues too; I probably have half a dozen Dell WLAN 1390 laptop cards I yanked and replaced because of issues with them, and the WLAN 1501 (wireless-N Broadcomm) isn't a whole lot better. There are some RA-Link options out there too, I haven't played with them enough to say much, but I don't use them because if I can use Intel, I do.
I've had Atheros cards for the Lenovo ThinkPad T60 and T61 that worked fairly well, but the quality control and shielding on the cards was far higher-grade than, say, an Atheros card made for an Acer laptop. And you'll find your home users often cheap out on laptops, resulting in cheap wireless cards.
One note - Dell is the least picky about swapping/upgrading wireless cards in laptops. You can put a lot of different cards in without issue. Toshiba, HP, and Lenovo all key their BIOS to require their-branded version of a wireless card (e.g., you need a Lenovo-branded Intel 5300, not an OEM-Intel); if the card isn't recognized (either due to manufacturer, or to being much newer or older than the laptop), the laptop won't boot. Workarounds include using a modified BIOS (which is what I did so my SO's ThinkPad SL could have a Lenovo Intel 6205), or in some cases, taping over (or using clear nail polish on) a certain pin or two on the wireless card.