Exchange High Availability

Hello,
I’m looking for opinions on high availability solutions for MS Exchange 2000.
I have been reading on a few solutions:
www.nsisoftware.com
www.legato.com
www.marathontechnologies.com
I was hoping people would have experience with some of these produscts and provide some opinions as to the best high availability solutions.
I currently manage an Exchange 2000 cluster. I’m not too crazy about it and I would like to be able to have a redundant offsite system with automatic failover. Ilook forward to reading some input into the subject.