Yeah, you won't be able to turn up the settings on your 560Ti - high is really all it's good for. But what you'll see is that you weren't really getting all of its performance at high using a q6600. Once you move to a 2500k, you should get 99% GPU usage, and you'll be at around 45fps all high at 1920x1200, or closer to 50fps at 1080p. Basically, while high would have been maxing out your GPU already, it maxed out your CPU instead.
You'll also open up the possibility of 560Ti SLI, which will offer amazing performance at high (probably 90fps), but don't expect to run all ultra - the frame buffer is still too small for either MSAA or ultra textures. You would, however, be able to turn everything else up to ultra. That's how I run my 5850 crossfire.
With a few things turned down, my 2600K (@ 4.8GHz) and my SLI 560 Ti 2GB cards (@950/1900/2004MHz) could run 64p maps on almost-maxed Ultra settings. I think I turned down World Mesh to High, and no Deferred MSAA (Post AA at top setting though). It became not a memory issue though, simply one of GPU performance. It's a lot, but it's not super top of the line.
Oh, and yeah, those settings kept me pegged at 60fps in vsync @ 1080p.
I have since turned off vsync to avoid input lag (though does it matter, since I am running SLI as well as using ASUS IPS monitors, versus faster TN panels?) and have the game itself cap at 60fps. Never new what the max average was, I think typically 80s. Sometimes it did drop below 50fps though, but never below 45fps iirc.
Not that it matters anymore - now that multimonitor support is fixed, I've been running with that the whole time. 6060x1080 (bezel corrected) is a ton of shit to render on these cards, and they hate me for it. My settings are a mixture of Medium and Low settings, and I can't remember if I ended up settling for no AO (HBAO looks gorgeous in this game).
The game still looks gorgeous, and I knew I'd have to settle for lower settings at this resolution for some games, as I have no desire to spend $1200+ on GPUs alone.
I thought I'd mostly run this resolution for iRacing and other racing games, and keep the new FPS releases on 1 monitor to get the best graphics with a smooth framerate.
But BF3 multiplayer is a blast in full surround. And this engine scales beautifully, it really does look great at lower settings. Not a home-run like the Ultra settings, but still it's a fair trade for the resolution.