How much RAM is optimum for Solidworks when designing free form complex parts when using a mix of surfacing and solids?  I don't do many assemblies over 25-50 parts.  Some of my parts start as imported surfaces from laser scans, which tend to lead to larger file sizes and cause more problems.

I don't get any out of memory errors, but do get some slow rebuild times, which may be due to my modeling technique at times.

I currently run

XP Pro x64 ver 2003 SP2

Dell Precision T7500

Intel Xeon CPU

E5530 @ 2.4 Ghz

6.00 GB of RAM

Nvidia Quardro FX 3800

Solidworks 2010 SP4.0 (should be upgrading to 2011 withing a few months)

I actually have two video cards installed, but I think I really only am utilizing just one of them.  (apparantly a Dell error, and they installed 2)

I will be soon adding a second monitor but have not thought too much about how best to incorporate that yet.

I know when I got this machine a couple years ago, the VAR told my IT that it would be "suitable" for running solidworks, but I don't know how optimum it is without going all out spending \$\$.

Any specific suggestions on where I am lacking or where to make the next upgrade?

Thanks!