Okay folks, nice big point topic as I think the answer will be quite complex.
The scenario is, we have three seperate ADSL lines into the building, 2x2Mbs and a new 8Mbs line coming in the next week or so. Currently we have about 40 PCs hooked up to the first 2Mbs line, and the email server hooked up to the 2nd (don't ask). If the main line goes down, it basically means that all the 40 PCs drop. Each user logs in via Windows 2003 SBS.
Each of the ADSL lines have a Belkin Router with DHCP enabled, and a Watchguard Firewall box attached.
What I WANT to acheive is to have the PCs spread over the three lines, with certain boxes going through certain lines (eg Reprographics goes through the 8mbs line) BUT to have a fall back in case one of the lines fails, all it's "users" temporarily switch to another line. Ideally I'd like to be able to control this centrally from the Server. Most of the PCs have fairly static IP addresses (in that they rarely change once assigned), but I'd rather not have FIXED IP addresses as there are number of laptops around the offices that sometimes go on home and/or other office networks. Hope that's none too vague for people.