Well without getting into to much detail, You may also drop your multiplier to 8 or 8.5 and raise your FSB to get closer to the Ram speed you want. This of course will depend on many factors but with your P45 board a higher FSB shouldn't be a problem at all.
Example: multi 8 X 400 will give you 3.2 Ghz and DDR2-961 (with correct FSB strap).
It's all a game of trial and error. You just need to go slow with small increases and test in between and you'll be fine. Oh, and don't overvolt and watch your temps.
I only have an older p35 and have my FSB set at 500 (had to bump up NB voltage 1 notch though).