PowerEdge 2950 questions

This question is related to the thread:
http://archives.postgresql.org/pgsql-performance/2006-08/msg00152.php
but I had some questions.

I am looking at setting up two general-purpose database servers,
replicated with Slony. Each server I'm looking at has the following
specs:

Dell PowerEdge 2950
- 2 x Dual Core Intel® Xeon® 5130, 4MB Cache, 2.00GHz, 1333MHZ FSB
- 4GB RAM
- PERC 5/i, x6 Backplane, Integrated Controller Card (256MB battery-
backed cache)
- 6 x 73GB, SAS, 3.5-inch, 15K RPM Hard Drive arranged in RAID 10

These servers are reasonably priced and so they seem like a good choice
for the overall price, and the above thread indicated good performance.
However, I want to make sure that putting WAL in with PGDATA on the
RAID-10 is wise. And if there are any other suggestions that would be
great. Is the RAID controller good? Are the processors good for database
work or are Opterons significantly better?

I may go for more storage as well (i.e. getting 300GB disks), but I am
still determining the potential need for storage. I can get more RAM at
a later date if necessary also.

Regards,
Jeff Davis