Is the traffic seperable by destination? In other words, is all the erp, citirx, and other mission critical traffic destined to one set of hosts/servers, and the remainder of the traffic destined to another set of hosts/servers? If so, you can create very specific routes for those hosts/servers along the "right" link, setting their metrics up so the right link is preferred.
The other option is to use policy based routing, and sort the traffic based on destination address, protocol or traffic type, and then setting the right outbound interface. If the primary is down, the traffic should fail to policy route, falling back on the normal routing table. For more information on policy based routing, see:
http://www.cisco.com/en/US/partner/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a00800c75d2.html
Russ.W