The only way one 9800 will destroy a SLI of 9600s is if it's the 9800 GX2, otherwise it'd be a pretty close match. the new 9 series is not supposed to be a big boost in performance.
Just as an FYI, I think it's been touched here, but the 8800 will still run faster than the 9600. Don't let that put you down though, the 9600 is "mid-range" while the 8800 is still "high-end".