Sounds like you have the right idea.
SSD for OS/boot drive. Crucial M4 SSDs have been good to us.
Put the the data on a business class NAS with RAID5/RAID6 or minimum RAID1 accessible via gigabit network.
We use ReadyNAS mostly as good combination of price/performance/reliability, though other brands do well also.
Keep in mind that offsite backup is a must, RAID is not backup. There are some reviews/articles on business online backup at OnlineBackupSpot.com