I would recommend considering the AMD/ATI 2460 display port graphics card. Passively cooled (quiet), low power, 4 displays capable. You really don't need an actively cooled graphics card for trading. They run about $250 or less.
I also think a dual-socket motherboard is a bit overkill for discretionary trading. I would go for a single socket motherboard with a quad-core CPU and with the money saved add as much RAM as possible: 16GB-32GB. Asus is a good brand for motherboard. Check out the Sabertooth Z77, but generally all their models are pretty good. Crucial is a good RAM manufacturer.
Definitely get an SSD. Use a larger traditional HD for backups if needed.
Keep in mind the less cooling fans you'll need the quieter the machine will be. Buzzing fans can get old quick. Even on laptops.
I also think a dual-socket motherboard is a bit overkill for discretionary trading. I would go for a single socket motherboard with a quad-core CPU and with the money saved add as much RAM as possible: 16GB-32GB. Asus is a good brand for motherboard. Check out the Sabertooth Z77, but generally all their models are pretty good. Crucial is a good RAM manufacturer.
Definitely get an SSD. Use a larger traditional HD for backups if needed.
Keep in mind the less cooling fans you'll need the quieter the machine will be. Buzzing fans can get old quick. Even on laptops.