Hi follow this http://forum.mikrotik.com/t/load-balance-multiwan-with-webproxy/38153/1 and adjust it to your needs, It works here in my setup, the only thing I notice is that it wont use the full speed of my adsl lines, I have 3 Adsl lines of 3500 Kbps each and the max throughput I get is 7.5 Mbps, I should be getting more than 10 Mbos. I have around 50 users and the max throughput I get is 7.5 Mbps I dont know why.