Which Quadro or GeForce for my needs?

Hello:

I am in the process of building a new computer. I expect to do little gaming (though I might play one or two on occasion) and wish to have a GPU suitable for realistic CGI/rendering, physical modeling and simulation, video editing and effects.

I have a budget of about $800 for the GPU and my set up looks like this.

CPU: Intel Sandy Bridge i7-2600K
Motherboard: GIGABYTE GA-Z68X-UD7-B3 LGA 1155 Intel Z68 SATA 6Gb/s USB 3.0 ATX Intel Motherboard (it has two PCIe x16 slots)

Memory: G.SKILL Ripjaws X Series 16GB (4 x 4GB) 240-Pin DDR3 SDRAM DDR3 2133 (PC3 17000) Desktop Memory Model F3-17000CL11Q-16GBXL

Would a Quadro or GeForce be more suitable for my needs? Will I see a massive performance difference between the two?

Also I had a question about PhysX. Some motherboard explicitly support it but are they talking about a specific slot for a PhysX card or the ability to utilize the PhysX integrated on current GPUs?

The obvious choice is a Quadro since you want to do CGI/Rendering. The Nvidia Quadro 4000 will suit your purposes and fit your budget. All the new Nvidia cards handle Physx natively on the card. For a time people were buying external Physx processors, but #1: they are no longer needed, and #2: if you read the actual testing, these external cards did not work that well and in some cases actually slowed things down.

A Quadro 4000 will suit your needs for a workstation and will play games just fine.