Background: I last rebuilt my rig in July 2010. I'm a quality-per-price bastard, so will not buy bleeding edge (have never needed to spend more than 250 on a vid-card) but work to future proof as much as possible. Due to this I have no pressing need to upgrade right now, my rig is doing everything I need it to do.
90% of my activity with it is the game Arma2, and I run between 20-40 fps depending on map.
The video card I have is becoming scarce so if I want to SLI I need to act now. However it's price is still high enough that I should consider tossing it and replacing with a more modern card. That could domino into a total new rig; which isn't really necessary now. This is the crux of my decision.
Option 1: Sjpend ~$210 on a 2nd video card (matched) to do SLI, to keep it running for another year or so.