Table 1: Primary Features of Exchange 2007 High-Availability Options

High-Availability Solution

Redundancy Offered

Failure Point

Backups

Additional Information

SCC

System only

SG*

Daily full backups

Cluster solution with automatic failover

CCR

System and Data

None

Weekly full backups with daily incremental backups; backup on the passive side by using VSS

Cluster solution with automatic failover

LCR

Data only

The Exchange server

Weekly full backups with daily incremental backups; backup on the passive side by using VSS

Not a clustered solution; requires manual recovery

*The belief that clustered systems running with NAS/SAN SGs are unstoppable has proven itself incorrect.
Your NAS/SAN storage solution can fail, and when it does you are left with restore from backups.