I have this setup right now and am needing a card.
Windows 7 Pro
(2)-ASUS VS248H-P Black 24" Monitor
CORSAIR Hydro Series H60 (CWCH60) Liquid CPU Cooler
ASRock Z77 Extreme4 LGA 1155 Z77 Intel Motherboard
Kingston Hyper X Blu 16GB
Intel Xeon E3-1245 V2 Ivy Bridge
High Current Pro HCP-750 750W Certified 80 PLUS GOLD
SAMSUNG 830 Series MZ-7PC256B/WW 2.5" 256GB Solid State Drive
3 -2TB Western Digital Black HDD
Rosewill 3.0 3.5 Internal Card Reader
1 Asus Blu Ray Burner 1 Plextor DVD Burner
I do extensive video editing and my software uses the GPU (Sony Vegas Pro 12). I also need a good one because when I edit I use a large screen for playback and the GTX460 I use now does a kind of lousy job for all of this. HD is a tough cookie to work with but it is so much nicer with the CPU I have now it is amazing. Most people game as I do not. Does it really make a difference if I have an intel setup to go with an Nvidia card? Anyone care to express their thoughts on this? Remember, I don't game. Thanks.
I would stay with Nvidia. As far as editing goes, they seem to have the most compatibility with CUDA. If I had to pick a card for you it would be the Nvidia 550 or 560. That will outrun your 460 and they are pretty affordable. Looks like a great build you have there.