Just some clarification, it will depend on the RAMin addition to the CPU and the FSB speed. The MOBO has dividers available to run the CPU and memory at different speeds but, there is no guarantee that DDR533 memory will OC to any speed above that. Keep in mind also that Intel does not provide dividers for the CPU to run faster than the memory so you may end up in a situation where the system will not boot at all.
Also, an E6550 CPU has a FSB speed of 1333 (333 x 4) as noted above which means at a 1:1 divider with the memory, the memory has to be able to run at 333mhz or DDR667 minimum. So, if you put this memory into the system and the SPD does not play nice with the CPU+memory combo and/or the memory cannot OC to 667, your system may not boot.
With your modern MOBO and CPU you will likely need some more current memory. However, the only way to know for sure is to install and test it.
The best option is listed above:
Get some DDR2 800. RAM isn't that expensive now days. $50-$80 buys you a 2*1GB or 2*2GB DDR2 800 kit.