Have you tried multiple lan cards on a server and feeding off that? I am set up this way and it takes less than 30 seconds for the switch over. The only problem is the different IP addys that each line uses. Some services will bounce you if to try to connect with the new IP without logging back in again. n.b. Windows server - probably works as well under Linux, but I cannot speak for that.
Dual WAN is the way to go since the router will keep the same IP assigned to the computer regardless of which line is actually feeding data. If you switch networks on W7 (possibly server 2k8 but never used it) its a royal PITA, you need to attach monitor + keyboard and select "work network" and add the new MAC address of the new router if running dual routers. If you go the dual router route and choose to run both into the same PC then I'd suggest using the same IP/Gateway for both routers and just assign the server a different IP address (say 192.168.1.10 & 192.168.1.11) where each router has both IPs and same gateway, DNS, subnet, etc. so that if one line goes down the system can easily adapt to the new primary feed and if you ever unplug the cables it doesn't matter which port you plug them back into. Also make sure you swap both intentionally so that both lines work on both NIC ports. Also need to set up remote desktop/VNC/general permissions & access on BOTH ports for BOTH lines so that you have full redundancy. If not you may have data but no access to your server.
Not the individual computer IP but the service IP. If one line goes down (say your cable modem) and the dual wan then switches to your dsl back-up, you are now running on a different IP addy, and some services will not allow you to stay connected with the different IP addy of your service provider. You would have to go thru the process of logging back in again, which will take some time. The setup I described above also works on your single machine with only 2 cards under WinXP - on a Mirus-zenfire connection, it took about 35 seconds to get reconnected automatically.
has anyone who uses a dual wan router had a feed go down ? - what happened next was the change-over successful or did you need to re-start your charting/order entry program/s again ? i have cable isp which went down once while i was in a trade, phoned the broker and closed the trade which started me thinking about purchasing a dual but have yet to do so, was thinking of Xincom but as J.P. said they're not answering their phone i was presuming the switch-over would be seamless and instant/continuous, but it sounds from what others have said above that it isn't at present i'm using Oanda FXTrade and MetaTrader 4 and can't remember what happened with them when the feed went down. MT4 i think could be left up and would re-connect, not sure if i'd have to re-login with FXTrade, NinjaTrader demo is time consuming, for one thing it can take a while to get it to close then restart for me includes re-loading the chart from scratch
The best result of dual wan setup is that you have a static IP and both of your ISP can route this IP address with gateway setup on both ISP end. This setup will cost your more, but it worths the money, and you can not tell the difference, when one link fails. Some major telcom will charge you arm and leg for this, but some local smaller ISP will do it much cheaper.
can't static ip be set-up for free - google: static ip - 'How To setup a Static IP Address' http://portforward.com/networking/staticip.htm