That's ok, I'll offer a more complete answer. 1066mhz ram is normally better than 800mhz ram. 4-4-4 is better than 5-5-5, it's how long it takes the ram to do specific things. So 4-4-4 is quicker than 5-5-5 at a given speed. Out of the three, the 1066mhz ram is the best as they all have the same timings, i.e. they're all 5-5-5.
For your processor, it has an internal speed and a speed at which is communicates with the rest of the system. The internal speed is 13 times the communication speed, the communication speed is called fsb. So at 3.4ghz, the fsb is 3.4ghz/13 = 0.262ghz = 262 mhz.
Everything in the computer is based around this fsb, you will overclock by increasing it from it's default. DDR2 ram runs at twice the speed of the fsb, that's what the 2 means here. So as long as your ram can run at least 262*2=523mhz, it wont hold you back. So the 800mhz ram is a bit overkill really. 1066mhz ram is a complete waste of time, it's useful for processors with multipliers of about x8 rather than x13.
I personally would buy
this, I've used ocz for a long time and am very pleased with them.
Throwing you in at the deep end a bit, if you let me know which parts you follow and which don't make sense I'll take another stab at it
