If you get the case I suggested, you'll want to get a couple extra 120mm case fans to help with airflow. The Antec 1100 only comes with two exhaust fans. One of those fans has blue LEDs. Feel free to change the case to whatever suits your preferences. Just make sure it has high airflow, good cable management, and makes you happy. Remember, you're gonna be staring at this thing while using it nearly everyday.
With your original build, I highly doubt you'd achieve 100 fps on a 120hz monitor. This depends on the game though. Even with my build, it may prove difficult to achieve 100 fps. I believe you'll need at least two gtx 670s in SLI to achieve this feat.
I typically don't recommend buying OCZ products. They seem to be rather unreliable. However, for under $200 for a 256gb SSD it's difficult to pass up. I'd so go for it. The vertex 4s are supposed to be much improved...especially with firmware updates.
Don't trust customer reviews. They're generally biased. And of course you're gonna run into input lag...especially if they were using a hdmi. HDMI doesn't have enough bandwidth to transmit images at 1920x1080 @120Hz. You'll need a dual link dvi cable for this to work with any 120Hz monitor.
Most people who give those reviews complain about technology they don't understand.