Question on High Availability

We are looking to deploy an offsite mirror of our critical systems (our mortgage app and email). I have 3 servers for our mortgage app which is web based running on Linux AS 3.0 Two of the servers run the app (apache/tomcat) and the third houses our Oracle db. Also, have email on FreeBSD running CommuniGate Pro. Which software vendor would you recommend to handle the HA failover and/or load balancing between the sites? Thanks in advance for your suggestions.