I would suggest that you get more than one HD, make the first one 2TB+ and have a secondary or even third at 1TB. Having lots of space for poser work and other media really is a life saver and it's always good to have back ups in multiple places.

For ram, 8GB is good but 16+GB is better. I'm assuming you're going to be on Win7 64-bit so the more ram you can throw at it, the more applications and complicated scenes you can have running at the same time.

The GT 610 is really a budget card, I think it's only 64bit so the bandwidth is really terrible for anything other than web browsing, you'll probably lag a bit in the Poser preview window with that card, but Poser doesn't use the video card or any of it's CUDA cores for rendering so if that's you're only concern then choosing the card will have no effect on render times and you can save some money.