Yeah, load balancing would only help you out if you actually had a LB box for a few servers(Such as Anand'sconfig)
Only then would all the traffic be routed to the less bogged down of the two connections and send the request to hte corressponding server. Then, and ONLY then would you see DOUBle the bandwidth.
You could also use 3com or intel cards, most of which support bonding, but that only serves as a redundant connection or for load balancing a server or line....if one server is fast enough(SCSI for access times, you could use the load balncer and send all requests to just one server, but other different lines😀