Vue is just far superior in quality when it comes to rendering than Poser. This is not to say you can't achieve quality with Poser because you sure can. But give someone with artistic quality both programs & I'm sure you'd see the difference. Once you've worked with GI & GR it's hard to go back to Poser. There is just so many cool features. I feel the only thing in Poser 7's favour compared to Vue is the price tag.

Regarding memory. I use Vue 6 Infinite but I only have 1GB RAM. This really isn't enough but I work accordingly. I won't have more than two figures in a scene & I purge my memory constantly. If you can downsize those textures then that will be a huge factor. The only thing is you'll probably need the large textures if you need the detail for high resolutions for print. But, problem again, if you're doing large file outputs that'll eat more memory as well.

Basically, if you can afford Vue it's worth getting. If you can afford more RAM, the better.