I'm running m0n0wall at an office, currently with DSL, and thinking
about adding a cable modem to the mix.  I'm not really interested in
load balancing, but what I want is failover so if DSL or cable goes
down, the internet stays alive.  Although utilizing bandwidth from
both lines would be good, it's not completely necessary.

T1 = $1000 a month minimum.  Cable and DSL = 160 a month.  If both
cable and DSL go down at the same time it would obviously be a telco
backbone in which case a T1 wouldn't keep working either.

Is m0n0wall capable of running this configuration?  I think there's
some variant of m0n0 that has failover according to google, but it
doesn't seem to be current.