Upgrade MacPro GT 120 to what? And why? (Video Editing Station)

At work we have a 2009 Mac Pro 2.93 QC Xeon for our video team to utilize. Originally purchased, it was outfitted with (3) THREE GT 120 graphics cards. Not even sure why. We only have one 30" Cinema Display connected.

Sidenote: Almost all of our video team members have Mid 2012 Macbook Pros (GTX 650M, 1GB). So they have quite decent machines.

We're in the midst of moving from FCP 7 to CS6. I'm trying to figure out if upgrading the GT 120 to a new graphics card would benefit our video team.

Software used:
Creative Suite 6 (Premiere and After Effects)
Final Cut Pro 7
Compressor
PluralEyes
Flip4Mac
Quicktime 7

Thanks!
-Spencer