Which brand of RAM itz good for overclocking?!?

Couple things, then I'll give you my choices.

1. Ram overclocking, gives the most negligible performs gains. Same with memory timings also.
2. The processor of choice you have, won't need overclocked ram to run at the rated memory speed.

I would rather put more money into a better CPU then put money on high memory rated ram /w cool heatsinks.

I've had good success with Cosair Dominators. 1066mhz ram was able to run at 1200mhz stable. Yours may vary, but by most reviews and user input, Dominators always overclock well.

@OP: The max for E5200 is 3.8Ghz OC.

So:
12.5*304 = 3.8Ghz.

You do NOT need any RAM higher than DDR2 800. There is no real world gain from OCing the RAM. Keep FSB:RAM at 1:1 and you'll be fine. I'd go with some GSkill PI Black RAM (2*2GB DDR2 800)

Also don't get the Scyth HSF. Get a S1283. It really isn't worth the $60+. (If you want quietness, head over to Petras tech shop and get some Yate Loon fans).
See: http://search.store.yahoo.net/cgi- [...] ate%20loon

I personally use these:
http://www.petrastechshop.com/12yalod1cafa1.html
(Yate Loon fans are very popular within the water cooling community)

If you already haven:

GUIDE: Overclocking On EP/P35-DS3L
OCing settings are smiler for all Gigabyte boards.

it depends on the chip your ram uses
if it's d9gmh just give it a lot of voltage and it'll get you where you want to go
i think for running default corsair dominators and g.skills are quite good
kingston hyper x also

Overclocking memory gives negligible gains in real world apps

You do NOT need to overclock memory in order to overclock your CPU

Overclocking memory is a VERY good way to make your system unstable