This link provides a little information on overclocking with a similar motherboard. The trick to memory settings is that different motherboard BIOS use different terms to achieve the same thing. From this link it appears that the right setting for MSI is simply 1:1.
If your CPU is running at 3.0 GHz then your main bus is running at 333MHZ and your ram (because it is DDR, "double" data rate) is running at 667MHz. You can do the math for faster speeds- there is a small chance that your CPU would run at 3.6GHz, in which case your ram would be running at its full rated speed of 800MHz.
If you google "msi q6600 overclock" you can probably find other people with the same motherboard and cpu that you have and see what their settings were.http://forum-en.msi.com/index.php?topic=119628.0