Building new computer mainly for photoshop - video card question

I am in the process of building a new computer for mainly photoshop usage. I take thousands of photos in RAW mode and want a fast computer that will hopefully last for many years to come. I basically have 2 questions

1) Is this video card good enough for Photoshop and its plugins (eg NIK color efex 4)
2) Is 16gb memory too much - would 8gb suffice

Here is the configuration I am thinking of. This configuration will cost me about $1,900.00 plus tax.

Video Card
Asus EAH5670/DI/512MD5/V2 ATI Radeon HD 5670 Chipset

CPU
Intel® Core™ i7-2600K Processor 8M Cache, 3.40 GHZ

Motherboard
ASUS P8P67 DELUXE (Rev. 3.0) Socket 1155 Intel P67

Memory
16GB - Corsair XMS3 Classic (4x4GB) DDR3 2000MHz CL9 DIMMs

Boot HD
Western Digital VelociRaptor 300GB SATA II 6Gb/s 10,000rpm

Data HDs
2 Western Digital Caviar Black 2TB SATA 3 Gb/s 64MB

Backup HD
1 Western Digital Caviar Green 1TB SATA 3 Gb/s 64MB (used for backup)

DVD
Pioneer DR-212 Black SATA 16X DVD R/W

Case
Antec Nine Hundred V3 case

Power Supply
Corsair TX850W PC Power Supply

CPU Cooler
Zalman CNPS9900NT Low-noise 120mm Green LED CPU Cooler

OS
Windows7 Professional 64bit OEM

Any suggestions or comments are welcome.
--
Bert D