HELLO beck92
I have a C2D E6600 and 2gb ddr2 just like you.
First tell me what motherboard you have and the ddr2 brand name and speed plus timing.
Second it is best to have a 2gb ddr2 800 (400mhz).(you can underclock you dram)
Third I would reconment to buy a after market CPU heatsink fan(Zalman is a good brand) and you must have lots of fresh air going into the case and have a good air flow e.g. a 120mm intake and a 120mm outtake.
OVERCLOCK:
1. Turn on your pc and hit "DELETE" to enter BIOS
2. Go to the section where do can change the fsb and voltage setting.
3. Change the fsb:dram ratio to DDR2 533 then incrase fsb from 266 to 350 mhz and disable spreatum. Leave everything on auto
4. Go to CPU feature and disable everything you see.
5. SAVE and EXIT.
6. While the pc restarts itself press enter again and then go to hardware monitor to see your cpu temperature wait there for a minute the temperature wouldnt go over 45*C(room temperature 30*C)
7. If everything is ok continu on into WINDOWS open up CPUZ and CORE TEMP and ORTHOS. Run ORTHOS for 30minutes and watch out for the cpu temperature.
8. If no erro were found by ORTHOS increase the fsb by 5~10 mhz and test stableness
FOR MORE INFORMATION:
http://forumz.tomshardware.com/hardware/Core2Duo-Overclocking-Guide-v1-ftopict197995.html