drive configuration for a new server

[Ben <bench@xxxxxxxxxxxxxxx>]

I'm looking to replace some old crusty hardware with some sparkling new 
hardware. In the process, I'm looking to move away from the previous 
mentality of having the Big Server for Everything to having a cluster of 
servers, each of which handles some discrete subset of data. But rackspace 
isn't inifinte, so I'm leaning towards cases that give me 8 drive bays. 
This leaves me with an interesting problem of how to configure these 
limited number of drives.

I know that ideally I would have seperate spindles for WAL, indexes, and 
data. But I also know that I must be able to survive a drive failure, and 
I want at least 1TB of space for my data. I suspect with so few drive 
bays, I won't be living in an ideal world.

With an even mix of reads and writes (or possibly more writes than reads), 
is it better to use RAID10 and have everything on the same partition, or 
to have data and indexes on a 6-drive RAID5 with WAL on its own RAID1?