i have an asus a7n8x deluxe with one stick of the same corsair xms memory. from what i have experienced, pushing your fsb farther will increase your performance more than changing memory timings. your motherboard should be able to hit fsb's in excess of 220 mhz, and if your barton is unlocked, then that would be ideal. if it's not, then maybe you could try 210x11, your barton should be able to hit that, and your memory can definitely take that. locked bartons tend to pucker out around 2.35 ghz.
I have had no problem with my temps running at 50-51 load.
I would move your ram down to the CAS2 that its rated for and slowly push the FSB up to find out when your ram quits. The extra fsb while holding your ram at cas2 would be my choice over going to a higher multiplier.