hello, i read the overclocking guide and i have a question:
i have an e6750 and ddr2 800mhz memory.
is the maximum overclock i can achieve is 3.2GHZ (8x400)?

It depends on a lot of things but you should be able to get to around 450-475 with that chip.

can anyone please explain what this line means?
"The number after it is the data transfer rate. Simply divide it by 2 to get the maximum FSB speed for which the module is rated. Example: 800/2 = 400 MHz. Therefore, DDR2-800 can work on systems with a FSB of up to 400 MHz (anything more and you’re lucky). "

The three limitations for OC'ing an Intel system generally are:
1. CPU core frequency limits - depends on the core, CPU voltage applied, and the thermal load on the core.
2. BIOS features and FSB limits of the motherboard.
3. Memory speed.

It looks like memory is the limiting factor in your system. When your FSB frequency is 400 MHz, your DDR2-800 memory is running at its rated speed. Your memory may run faster if you are lucky. You can also squeeze more speed out of the memory by raising the memory voltage if your BIOS will let you. You can also try relaxing the memory timing values. If the standard timing is 4-4-4-12, change it to 5-5-5-15 or even 6-6-6-18.

so what i said was correct?
by keeping the memory in its stock clocks i m limited to 3.2GHZ overclock?