Cisco WAN :: 800 Router That Support Dual Wan Capability

i've searched the cisco product line looking for a simple router that many of my small to medium size clients can benefit from .Most of these clients have approx.  40 - 75 users and they have standard T1 Connections for Internet as well as a secondary Internet provider utilizing broadband ( cable )
 
 i would like to find them a cisco series router that can provide both load balancing to maximize the speed from both ISP's and -  provide automatic fail-over / business continuity in the event one of their Internet lines goes down.
 
i see that the 800 series router provides business continuity but it doesn't appear that is suitable for my situation ( T1  / broadband cable )  not DSL.don't want to spend 5k on something that is overkill b/c again, these are relatively small offices ( 40- 75 users  max )