Check these 2 charts/webpages...
http://www.videocardbenchmark.net/gpu_value.html
http://www.videocardbenchmark.net/high_end_gpus.html

And follow the cards on sale at deal sites like
http://www.fatwallet.com/video-card-deals/
http://bensbargains.net/categories/video-cards-35/
http://www.techbargains.com/catsearch.cfm/0_2_5

http://www.notebookcheck.net/

to check what I was looking at. I don't know how accurate their tests are, but it's a quick way to get a sense of what you want.

I currently use a NVIDIA GeoForce GT 730M and so far I've played Skyrim on high settings with no problem. When Dragons begin raining down upon me, I might set it back to medium, which the above site tested it best for.

I am using an old Radeon 5670 that i bought tbree years ago and it plays most games on medium settings today on a 22" 19something by 1080p monitor.
I have to thank the poster above for the passmark chart,looks like i need the Geforce GT 560 TI for my next upgrade and the price is where i usually spend anyway.

My upgrades usually go on a three year cycle to keep on the back side of the hardware curve.
Let the fraternity Oy Boys spend daddy's money on the enthusiast stuff,to me the top shelf stuff has never has been worth the price.
Unless 10 more FPS and a few less nano-seconds are important to you.
Then by all means get the Titan or the fabled 7990,they are only 1000 bucks.

One useful word of advice though unless you do game design or CAD or AutoDesk ignore the Radeon Fire cards and the Nvidia Quattro cards in the PassMark hierarchy.

With the 700 series out, GTX 770 seems to be the best bang for your buck if you're working with one monitor. If you have more monitors, get the 780. Currently have the 680. Wish I would've held off for the 780, but that's ok. Have an old 470 card on another pc that can be replaced when I do make that plunge.

What kind of processor are you working with?

Screen is a Samsung Syncmaster SB300 24", and it's for a desktop. My CPU is a Core i3 3.30 GHz, but the bottleneck is really the Intel HD integrated GPU.

I would build a new pc if I had the time and money, but for now I'll just try and see if I can tweak the one I have a bit.