Super quick, just thrown out in the hopes it may save some Googlers some time: I was getting really slow wireless connections on my Buffalo WLI-UC-G300HP adapter with intermittent disconnects. This link had the clearest directions, although:

• usb_buffer_free and usb_buffer_alloc had changed in the most recent kernel
• needed to add a device code for my adapter
• did not need to update the firmware or the USB list

Anyway, patch is here if you need. If you’re absolutely desperate and you’re running my configuration (Ubuntu 11.04 64-bit on kernel 2.6.38-8) and you trust that I have no nefarious intent then you can pull rt2870sta.ko from here and put it into /lib/modules/2.6.38-8-generic/kernel/drivers/net/wireless.