Regarding Time Machine backups - do a google search on issues with it. You will find a number of ways to help with Time Machine - especially if you are trying to do this wirelessly.
I am not sure what people are expecting the My Book to do connecting wirelessly and with a 10/100 connection. It can only move the bits as fast as the wireless speed. Try connecting the My Book Live directly into your computer via the Ethernet port to test the speed. As long as you have Gigabit ethernet, you should see anywhere from 40MBs-90MBs (depending on the size and length of files you transfer. The larger the file size, the better performance you will get).
If you are still having issues connected directly, then you might start investigating your OS. Antivirus software can slow down performance on file writes by up to 40% (depending on the AV vendor).
Tony
