Not really. Only if the Multi is locked. Q6600 = x 9 multi, so thats 400 x 9 = 3.6 And DDR2 @ 800 Mhz. So in reality, you'll get at least 20 mhz over that on normal type ram.
So 420 x 9 =3.78 and 840 DDR2.
Decent OCers Ram can keep its timings for longer, Say 435 x 9 = 3945 and 870 for yer ram.
Do you need more speed than that? Just be sure to get 4-4-4-12, because most major brands can hit 1066 ish at 5-5-5-15.
--Lupi