I overclocked my Dual Core E2200 Processor from 2.20Ghz to 2.40Ghz using the BIOS, i was using a tool "ASRock OC Tuner" but apperently when you shut down windows everything gets disabled, also alot of people say on forums to avoid using Tools, so i decided to give it a shot using the bios.
As a beginner, i spend like a week reading internet articles about overclocking and watching Youtube tutorials, and finally managed to do it, but i have noticed, that when the CPU is not in use, on windows and web browing basicly, the temperature is around : 48/49/50 Degrees, and am using the stock fan so i really don't have the money to buy an aftermarket fan right now, but am seeing alot of people who managed to overclock the E2200 up to 3.00Ghz with the stock fan, so basicly just wanted to give it a shot maybe it works for me and save me some money, i can do it instead of buying a new CPU. also i have a good graphics card GTS 450 and 4gb of ram, only thing that's disturbing me in gaming is the CPU that is too slow, so i decided to overclock it maybe it will give me better performances.
So here is what i did, tell me if everything is alright :
-1- I pressed F2 and entered the BIOS.
-2- I went to CPU config ==> Overclock mode : CPU, PCIE Async
-3- I set the CPU Frequency (Mhz) to 
(My CPU multiplier is 11 so i set the Frequency to 220, and 220 x 11 = 242 (2.42Ghz)
-4-Then i went over to Chipset Settings and i set the DRAM Voltage to [2,201V]
-5- Save and Exit
The PC shut down and restarted normally.
There you go that's all i did, i'm a begginer please if i messed something tell me so i can fix, other then that tell me if i should go for more 2.40Ghz was just to test, now that it worked probably i should go for more but i don't want to cause too much overheat.
Man, I think you could do fine. I would, however try to get my hands on something like a Coolermaster Hyper 212 Plus, though. MAKE SURE YOUR CASE DIMENSIONS WILL ACCEPT A LARGE COOLER, THOUGH. XD
Its only like 30 bucks or so, and is one of the best cpu air-coolers ever sold on the market at a rediculously low price. Seriously, look at the tests people did with it, its amazing. That aside, how good is your cases airflow? If your case is getting hot inside, not only are your tempts going to be seriously wack, your CPU will throttle if you dont have options to disable Intel Speedstep and Intel TM technologies.
That said, my E6750 with a multiplier of 8 and default FSB of 333 is currently cranked up to 410 bringing the 2.66GHz CPU up to 3.30GHz. Thats 700Mhz. I can successfully achieve about 850MHz overclock before serious instability. I think if you can keep your CPU cool, your little monster of a CPU has tons of headroom. Leave your voltages on auto, make sure your power supply is sufficient and reliable, and that your case and CPU are able to cool properly.