We really wouldn;t be able to tell without knowing what mobo and BIOS version you're running.
Only being able to up the Bus speed will not mess with your temps really at all since the vCore isn;t being altered (voltage).
However, the stock HSF on C2D's suck... biiig time. I'd suggest just getting the AF7.
Your mobo may have the FSB:RAM Timings linked, but probably not. It all depends on the mobo.