This week I switched to #! (Crunchbang) because my Ubuntu was getting slow. I love the speed and was very happy with the wifi because it had the b43 driver working by default. Except, I could not get on my network after the most recent upgrade, but I found a work-around after a day of reading forums. Surprisingly, it’s not too complicated! You just need to create a conf file for b43 to use PIO and it will not through a DMA error anymore… my hardware is: Broadcom Corporation BCM4312 802.11b/g LP-PHY [14e4:4315] (rev 01). This is the only line you should need.
sudo echo "options b43 pio=0 qos=0" > /etc/modprobe.d/b43.conf
Reference: This article from Ubuntu Forums.