At this point you should find the failure points of your mobo and RAM. Bump your multiple down to keep the CPU speed at 3.0 or less, and keep raising FSB till failure. Use the lowest RAM multiple you have available. You have 1066, so you should have plenty of headroom for FSB.
If your FSB is choking, you'll need to start tweaking BIOS settings and finding what makes it more stable. Then you can go back to overclocking the CPU.
The only catch here is that even though your RAM is rated for 1066, it may be failing at lower speeds because it doesn't play nice with your NB etc. If tweaking board settings isn't helping FSB max, you may want to look at more VDIMM or loosening your RAM timings.
What are you at for FSB and RAM right now?