Actually, wired are usually 10/100MBps (can also buy 1000MBps cards) and wireless can get up to 108MBps with the SuperG technology. High speed broadband connections are typically between 1.5MBps and 5.0MBps....depending on the area. DSL is averaging around 750Kps (once again depending on the area). What is the average speed in your area? What you should aim for is to get a speed high enough for your needs. Most people only need 10/100 MBps connections because this is a theoretical bandwidth. You dont want to limit yourself. You'll VERY rarely be able to D/L a file from the internet at 3MBps but if the bandwidth is there....then all the better. The technology is cheap too, so why not buy it? Also, networking doesn't have to include the internet. Companies and other LANs just want a fast and reliable connection locally. So, if all equipment in a LAN can handle a theoretical 100MBps than you'll never have an issue with speed across it.
-Mike