Help specifying new web server/database machine

I'm tasked with specifying a new machine to run a web application
prototype. The machine will be serving web pages with a Postgresql
backend; we will be making extensive use of plpgsql functions. No
database tables are likely to go over a million rows during the
prototype period.

We are considering two RAID1 system disks, and two RAID1 data disks.
We've avoided buying Xeons. The machine we are looking at looks like
this:

Rackmount Chassis - 500W PSU / 4 x SATA Disk Drive Bays
S2882-D - Dual Opteron / AMD 8111 Chipset / 5 x PCI Slots
2x - (Dual) AMD Opteron 246 Processors (2.0GHz) - 1MB L2 Cache/core (single core)
2GB (2x 1024MB) DDR-400 (PC3200) ECC Registered SDRAM (single rank)
4 Port AMCC/3Ware 9500-4LP PCI SATA RAID Controller
80GB SATA-150 7200RPM Hard Disk / 8MB Cache
80GB SATA-150 7200RPM Hard Disk / 8MB Cache
250GB SATA-150 7200RPM Hard Disk / 8MB Cache
250GB SATA-150 7200RPM Hard Disk / 8MB Cache
Slimline 8x DVD / 24x CD-ROM Drive
Standard 3yr (UK) Next Business Day On-site Warranty

I would be grateful for any comments about this config.

Kind regards,
Rory
--
Rory Campbell-Lange
<rory(at)campbell-lange(dot)net>
<www.campbell-lange.net>