802.11b carries the advantage of being a widely available standard. With 802.11b you will be able to (for a fee) use your laptop in coffee shops, airports and other public places. It is also more like that if your work has wireless access, that they have adopted 802.11b and therefore your can move from work to home using the same equipment. If those things are important to you, get 802.11b. While it does share the same 2.4GHz spectrum as many other devices and can interfere with cordless phones, it is possible to configure the channel range used. Typically most phones use the low channels. I have generally found that moving to higher channels tends to solve most of these issues.
802.11a operates on the 5GHz band. It is less crowded that 2.4GHz (for now at least) and supports higher bandwidths. If you are just using the wireless link to connect to the Internet, then that is not a big concern - 802.11b is faster than any Internet connection you will have around the home. But if you are using it to connect computers on your local network and do a lot of file transfers between machines, then that might be a concern. 802.11a also tends to be more expensive than 802.11b as it has not reached the same economies of scale.
802.11g is just beginning to appear. It remains in the 2.4GHz channel space but allocates more bandwidth in order to get higher throughputs. At this point, I do not see any compelling reason to adopt this new standard in the home.
Hope that helps and good luck!