P5Q SE Plus

Hi, I just bought a p5q SE plus mobo with a Intel q9550 and it's all workin great but I dont really think it's optimized in BIOS.

Start with some specs:

http://valid.canardpc.com/2709515


The first i noticed when i bought the stuff is that it was 2 different types of memorys, one type of 1066mhz and one type of 800mhz so I ripped out the 800mhz and replaced them with my Kingstons. He told me he had to underclock the memorys to 800 so the system would be stable. I dont have that much of experience in BIOS but I've been around so with some help from you guys I'll prob make it  

So my questions are: What kind of static changes shall I do? I tried to just load defualt setting but that bluescreen me like a bauss! Is there any programs that can check my mems speed?

and oh, btw, he had 2 profiles in bios one of them was with OC so the CPU got up to 3.5 ghz but the memorys was set to 850mhz but before clockin the CPU i want everything to be stable and correct.