Two internet connections: how is better

I am seeking an opinion on how to set up 2 internet connections the best way. What I have is a LAN of around 45 workstations and around 10 servers which serve the LAN as well as Mail, Citrix and VPN connections to WAN. The internet connections are: ADSL 1MBit/128KBit and ADSL 1.5MBit/256KBit.

I have thought of 3 setups:

1. Put both connections to the same switch (through firewall). Setup up the weak line as a def. gateway for the LAN and the powerful one as a def. gateway to the servers. This way servers will have begger channel for serving WAN with all the stuff.

2. Put each connection on a separate switch, connect LAN to the switch with weak connection, add second ethernet for each server add connect each of the servers to each of the switches. This way LAN will be accessing WAN through the weak line and servers through the separate servers\’ ethernet while servers will have second ethernet to serve WAN through the big channel. This makes me feel like I will reduce traffic on the LAN since WAN serving will be done through the separate ethernets and also I will have more accessability to the servers since they have 2 ethernets each.

3. Do the 2 and then make a failover between firewalls on both internet connections so that in case one of the lines goes down, the second line will be used by both: servers and LAN.

I am new to setting 2 internet connections, but knowing that there are a lot of people on the web who did it many times I am seeking comments, advice and whatever is applicable here.