You may have another issue here, I know there are problems with resources and stuff, I've bitched about them enough myself.
However, if you care to look at the Vue images in my gallery here, every single one uses the Poser Shader Tree and is reasonably complex with lots of materials and Poser items, yes I had to purge memory a lot to get them done but I did get them done, not ideal I know but it can be done.
If you look at the threads here, you'll see me pop up quite regularly slagging off the resource issue of this software, that said i have also said this: It's the best bit of software I use, period [resource issue aside].
Maybe look for another reason for your issues, I don't have as much RAM as you [2 Gig] and I'm still sunning on a Pentium 4 HT 3.4 GHz and I use Vue6Inf.

A question: Are you running Vista as your operating system??

Injustice will be avenged.
Cofiwch Dryweryn.