Its gonna be as stable as your ADSL connection, but you could go for two permanent IP ADSL`s with different providers on two lines. I`m sure it can be configured to work like that.

A good friend of mine has been running his company website on the end of a 256 upload ADSL for over a year in the UK, the ADSL went down for three days once but thats the only down time he`s had and because it was a road digger that went through some major cables in the area everybody was out regardless.

chmod