They'll populate the DIMM slots with 1 Gb DIMMs. If I upgrade to 3 Gb, all 4 slots will be filled since it's dual channel RAM. I noticed that there's an option to get 800MHz RAM instead of the 667 MHz they provide as a default. It's probably worth spending the $20 to get the faster RAM.

Since I'm going with 32 bit XP Pro, I'm not sure that there's much value expanding beyond 2 Gb due to the internal limitations of that OS. 

As I put my configuration into the shopping cart, I found out that there's free shipping for systems over $600. Shipping will cost me $30, so it's probably worth spending $50 more in an upgrade since it will only be $20 more out of pocket.

My visual indexes of Poser content are at http://www.sharecg.com/pf/rgagnon