partitioning server

[Patton Echols]

I am building a server that will have fairly low traffic for home use.  
The primary uses are data storage and backup for a mixed linux/windows 
home network and offsite / remote backup of my office network.  It is to 
be a three disk system, the "small" disk, 200gb, will hold the OS and a 
pair of 1tb drives will be configured RAID 1 for the data. 

Since this is the first time I have built a server, I don't know if 
there are best practices for what should go where.  Anyone have thoughts 
they can share?