None of those; I'd go with these Corsair:
http://www.newegg.com/Product/...x?Item=N82E16820145590 ($34 after rebate, with free shipping to boot).
Remember, OCing RAM on its own does very little to boost performance; they key is just to have RAM fast enough to keep up with the CPU overclock (i.e. the FSB). Current motherboards support 1333MHz FSB, and some support 1600MHz FSB. DDR2-800 is the correct speed for 1600MHz FSB, so it's unlikely you will need RAM faster than that.
The e2xxx and e4xxx are designed to run on an 800MHz FSB, so running on a 1600MHz FSB is a 2x overclock, which should be plenty (if the CPU core even supports that speed). Certainly no need for RAM faster than DDR2-800 for these.
The e6550 is designed for 1333MHz FSB, so running it at 1600MHz gives only a 20% overclock. Overclocking it further should be possible, but will require running RAM faster than DDR2-800, so overclocking the RAM or using faster RAM would be needed here.
IMHO, since an e6xxx or e8xxx CPU costs more than an e2xxx or e4xxx and requires much more expensive RAM for a substantial OC, your best bet is an e2xxx or e4xxx.