I switched my old Toshiba Satellite A105 from Windows XP to Lubuntu 11.10 and used the Update Manager to make everything current. The kernel is 3.0.012 and the wireless card is an Atheros 5000 series. The wireless card was working fine in Windows but after the switch to Lubuntu the apparent speed of my connection went down to almost nothing. I googled the problem and came across a workaround in this thread.
Though the workaround given was for the 9000 series, I found it solved my problem too with just a simple change for the 5000 series drivers. Add or create /etc/modprobe.d/ath5k.conf and add the following:
options ath5k nohwcrypt=1
I rebooted the system and now my connection is back up to par.