I have used both, I have the same Atheros chipset in my desktops, not card mind you, and the Intel 2915ABG Card in my laptop.
I have to say I would go with the Intel card over the Atheros card for a few reasons. First, I prefer the Intel ProSet for Wireless over the Windows Utility or the Atheros Client Utility.
The Atheros cards also have a problem of not resolving an IP address "sometimes" when resuming from sleep, which makes me have to enable/disable the card or reenter and exit sleep. The Intel card also supports wireless A, however it doesn't support SuperG(108MB/s) like the Atheros. Although both these features are rather useless since there are few A access points, and SuperG requires an Atheros access point. Finally Intel is more opensource friendly and now have an in-tree driver for the 2915