Since I promised to report my findings...
After running some basic benchmarks w/ RAM at 700 mhz, 1:1 ratio, 4-4-4-12 vs 875mhz, 4:5 ratio, 5-5-5-15, the 875mhz showed better performance in both ram and cpu tests (no changes to cpu settings). So I guess 1:1 isn't as important after all, with the core 2's. The only thing was lower in the faster ram speed test was floating point math, 641.2 MOps/sec to 667.8 MPps/s, whatever those are.
After running some basic benchmarks w/ RAM at 700 mhz, 1:1 ratio, 4-4-4-12 vs 875mhz, 4:5 ratio, 5-5-5-15, the 875mhz showed better performance in both ram and cpu tests (no changes to cpu settings). So I guess 1:1 isn't as important after all, with the core 2's. The only thing was lower in the faster ram speed test was floating point math, 641.2 MOps/sec to 667.8 MPps/s, whatever those are.