Ignore the system specs from Smith Micro. They are the bare minimum - only sufficient to make your system crawl and hang and frustrate you.
Buy the best graphics card you can afford and the most memory your operating system can handle.
A dual-screen setup is very nice. Don't know how I managed before, but I did, after a fashion.
Make sure your machine is well  cooled if you upgrade an older system. You may need an extra fan.
Disk space - you'll need lots. Once you get hooked you'll start accumulating content - figures, models, skins, props, texture images, etc.. Even if you stick mostly to free stuff from here, Daz, AdamThwaites, ShareCG etc, you'll soon need an external hard drive.

Welcome to the madness.

Poser 11 Pro, Windows 10

Auxiliary Apps: Blender 2.79, Vue Complete 2016, Genetica 4 Pro, Gliftex 11 Pro, CorelDraw Suite X6, Comic Life 2, Project Dogwaffle Howler 8, Stitch Witch