In my production environment I am running Oracle on Solaris 9 on a Sun
Fire V440 (2x 1.5cpu's and 4gb memory). The Databases are stored on a
NAS device not locally. I am looking to upgrade my computing power and
am looking for opinions on the best upgrade path. We are looking to
roughly double the amount of traffic on our website (driven by the DB)
over the next 6-12 months and want to be prepared.

I can upgrade the memory on the current server to 8GB from 4GB (not
sure on cost yet)
I can add 2 additional CPU's with 2GB each to get to 4CPU / 8GB (not
sure on cost yet)
I can buy an X4200 with 2x dual core, and 8GB memory. ($8,195.00 on
their website)

The x4200 sounds really appealing but I am almost scared because it is
so 'cheap' compared to another V440.

My budget is around $10k, i'm just now starting to research the prices
for the first two upgrades. I'm looking for the best performance for
my $.
Our database is a classic OLTP database with the database mounted on a
NetApp filer over gig ethernet.

I am also not shy about not using Solaris on the x4200 if other admins
had better results with another distribution and Oracle.

Thank you for your input.