Optimal Postgres setup with 6 disks total (including OS)

[Josh Bonnett <joshua.bonnett@gmail.com>]

Hi, I am looking at buying a server with 6 36gb 15k rpm scsi disks in it 
and I was wondering what people would recommend for a disk setup. The 
six need to include the os and such. As it is right now we are thinking 
1 4 disk raid 1+0 volume for postgres and 1 raid 1 volume for os and the 
swap file. Getting a 7th disk is economically impractical. What do 
people think?  This is a fairly write heavy db compared to some so I was 
thinking it would be good to avoid raid 5 or am I wrong here? What do 
people think?