With a recent bonus from work in the bank, we decided it wouldn't bust our budget too badly if I threw about $230 into some hardware.

That's not enough to get a new motherboard and CPU, but thank God my i7 920 is so overclockable.  I already pushed it from 2.66 GHz on stock to 3.3 GHz on a Zalman air cooler.  So I found a Corsair Hydro h60 on sale for about $60.  One hour later, I'm rocking at 4 GHz on four cores and my stress test is hitting them with 100% yet they won't break 75 degrees C (max is 80 degrees C for this chip).

That's about $170 left.

At this point, I could either get a Nvidia 650 on sale for a little more than that, or I could get another 560 Ti for $160 and get the same performance.  A second 560 Ti it is.

Word or warning: do not order hardware late at night.  I accidentally ordered a 560 first and now have to return it after learning a 560 cannot do SLI with a 560 Ti.

Then I realized my motherboard is not SLI-ready.  See warning above.  Luckily, I was able to flash the BIOS with the BIOS of another board from the same family that is SLI ready.  Phew.

Finally, I found a SLI bridge at a local mom and pop shop for $10.

$230 later and I have added another 50+% to my GPU and CPU.