Okay, I've got a GTS 250 512mb. It works great but doesn't support DX11. I want to upgrade to another card with DX11 support. I've got a 19inch monitor and run my games at 1280x1024 so I don't kneed anything too powerful. I'm just looking for something that will give me a similar level of performance as the 250.
My specs are as follows:
-cpu: AMD Phenom IIx4 955 3.2 GHz
-mobo: Asus MUA77TD Pro
-ram: 4GB DDR3
If you do want to spend a bunch, get a GTX 560Ti for $200. It's your call. But the GTS 450's pretty much a sidegrade, not an upgrade.
If you have $200, you'll end up happiest spending $120 on a 22"/21.5" monitor and $80 on a GTX 460 768MB.
Then overclock that graphics card to really get your money's worth. That'll be quick and easy with MSI Afterburner/Kombustor. PM me if you want to start a thread on graphics overclocking and I'll walk you through it. It'll only take 30 minutes if you know what you're doing for a 20% performance bump--and 2 hours if you don't know what you're doing.