Yep this is true, the bcm43xx wireless modules can only handle up to the 11Mb/sec connection which is why it is not included in my custom kernel(which is your clue).
Custom rebuild the kernel from source and disable the CONFIG_IEEE80211_SOFTMAC option;
# CONFIG_IEEE80211_SOFTMAC is not set
Then after booting to your new kernel download/install and use ndiswrapper for you wireless device;
http://ndiswrapper.sourceforge.net/
You might want to get ndiswrapper beforehand.