802.11b and 802.11g are utterly obsolete and must now be disabled by all access points, routers, and clients.
802.11b first emerged in 1999 - a hot new standard that provided inexpensive networking over the air. But by January 2003, a faster standard became commonplace - 802.11g. And since 2006, 802.11n based products have been on the scene.
Both 802.11b and 802.11g are inefficient. These protocols consume valuable wireless bandwidth and manage to slow everyone down. And therefore, I proclaim that 802.11b and 802.11g must be immediately banned from the world. Doing so will speed access for everyone.
So log into your access points and disable the mixed modes that support anything below 802.11n. Throw out your old interface cards and routers. You, and 99.99% of the rest of the world will see much better performance. Never buy a product that doesn't support 802.11n or better.
Upgrades are very inexpensive: 802.11n USB client interfaces are available for under $15, and 802.11n routers can be had for less than $25. At this point, there is simply no reason to have the obsolete protocols around.