Well it depends how you want to use it IMO!
There are those here that will say your system is enough which is fair enough if you don't want to use all the latest good bits, i.e. the Poser Shader Tree and reposing inside Vue, displacement materials, SSS materials etc. which I like to do. All my Vue work includes Poser figures and I ALWAYS import with the shader tree and allow reposing!
IMO your system will not allow you to do that with biggish scenes, I would recommend at least 4 Gig RAM if you want to work in that way.
There are work arounds which others will be glad to give you but for me, if an app. says it can do this and that then I want to be able to do this and that, not work around it!!

Now to your question, My spec:
Quad core Q6600, 8 Gig RAM, Nvidia 8600GT or GS [can't remember] Graphics, 2 x 250 Gig HD's in Raid 1 array, Vista Ultimate 64

This system allows me to use Vue how I want to use it and I can use all the bells and whistles that come with it which is the whole point for me!!

Injustice will be avenged.
Cofiwch Dryweryn.