Workstation RAM advice

[tricky]

We are in the process of buying new workstations. We have the option of going for 4GB PC2-6400 800MHz Dual Channel Low Latency RAM (4 x 1GB sticks) or 8GB 667MHz (4 x 2GB sticks).

In my heart, 8GB sounds better (we do a lot of Photoshop with 300MB files open, together with sessions of ADT and MAX open at the same time) but from the specs, the 4GB option uses faster RAM.

Anyone have any opinions on this? Would 8GB be better even though the 4GB uses faster RAM?

[apexmotion]

I would go for the 8GB, but I'm no expert. I just noticed that nobody replied, so I thought I'd put 2 cents in.

Along the same lines, I was wondering....

If I normally require 2GB to open scenes on my single-core system, should I get 4 x 2GB = 8 GB when I go to quad-core? Or is the scene only loaded once in memory and each core just needs marginally more to render its bucket?