I have to setup a wireless router here and wanted to do some reading while I wait for my items to arrive.
I found a decent beginners article on the TigerDirect Site that has some pretty good information, includging a nice breakdown of the differences between the four standard protocols; 802.11a, 802.11b, 802.11g, and 802.11n.
802.11a - Bandwidth up to 54 Mbps
Due to a higher frequency range, this standard may not have as much distance as other options. Was created about the same time as 802.11b
802.11b - Bandwidth up to 11 Mbps
Uses the 2.4GHz radio signal, which is common for other devices such as microwaves and wireless phones, so it may have trouble with interference from other devices.
802.11g - Bandwidth up to 54 Mbps
Uses the 2.4GHz frequency, but supports more users and has a greater signal strength.
802.11n - Bandwidth up to 300 Mbps
Uses the 2.4GHz frequency, and supports more users than 802.11g and has the best signal strength of the 4 options.
It is also important to note that 802.11g and 802.11n are backward compatible with 802.11b.