Which backup solution do i require?

Hi

We have 2 physical servers each hosting 2 virtual servers

2 of the servers are in a failover cluster and one has exchange 2007 (all of which need to be backed up).

So including the virtual machines there are 6 servers, there is also a SAN which they may or may not want to be done.

Also when it comes to large backups like this what sort of media would you recomend for the backup?

Many thanks

Doug