Broadband starts technically at 600bit/s (0.073kb/s).

Select you speed based on your max upload speed unless you have a symmetric connection with equivalent upload and download speeds (e.g. ISDN, SDSL).

In LimeWire are the speeds assigned as follows:

Modem = 56kbit/s
Cable/DSL = 350kbit/s
T1 = 1000kbit/s (~1MBit/s)
T3 = 3000kbit/s (~3MBit/s)