why do you think you need a quadro card?

the only place youll notice a difference with the quadro is that it supports hardware line antialiasing which is a big plus in some high end 3D apps and CAD applications. 

otherwise there will be no significant difference between a $1000-4000 workstation card and a ~$200 mainstream enthusiast gaming card in Poser. youre just pissing away a lot of money for something you wont benefit from and will be obsolete in 24 months.

even high end apps such as Mari are being optimized to run on much more affordable gaming cards like the GTX 480 and 580 (and BTW also run fine on a 560ti, 570).

 

IMO you are spending way too much money on this rig. computers are not an 'investment', and you could build something that would give you the same practical Poser performance for 1/3 of the cost.
component prices have dropped significantly. you can build an excellent machine for ~$1500 these days.

also - if youre getting 'quotes' for builds you are already shopping in the wrong place, and are forking over hundreds of dollars in profit margin to someone with each component upgrade. your best bet for building a system is to find a great deal on a preconfiged system or, preferably, an online parts retailer (like Memory Express in Canada) that also offers a system build/OS install service (usually for a paltry fee like ~$75) - theyll deal with any DOA/defective parts and compatibility issues onsite and usually warranty the build as well.  if youre talking to a sales rep and getting 'quotes' on high-end builds youre already getting ripped off.
just my $0.02, coming from someone who worked in Dell business sales for years.