I'm not familiar with AI Overclocking since i use a Gigabyte board, but yes, use manual overclocking. It may be that the rams don't like having their bus speeds changed... you can leave them alone for now, focus on one bit at a time.
With everything at defaults, pump up the fsb by increments of 0.1 ghz or so (usually i like to take big jumps for the first time, since i know its possible) though you shouldn't stretch it too far. You're not using any overclocking heatsinks so i'd suggest 3.3 Ghz safe for starters.
Go into windows each time and check stability. If unstable, add a little or less vcore and see how it affects, if not turn down the fsb or sometimes even turn up.
I've heard of strange occasions of cpus not liking certain speeds i.e. will boot at 3.2ghz, will not boot at 3.3. but will boot at 3.4ghz
Play around but be gentle with your numbers. Once you find a good core speed and is stable, start tampering with the 1:1 ratio of your ram.
My guess would be that 3.6ghz be your golden number. 400 FSB, 400 Mhz ram, so the full DDR2 800 at synchronous.