well i would consider these things also, but to answer you question of where to go to overclock it, you go to the bios. to get there you restart your computer and press either delete or f2 depending on your mobo. then you increase the clock speed by the smallest possible increment(mine goes by 1mhz). after you increase it, continue to the boot. download prime 95 or 3d mark. these are cpu/vga stress tests. if your computer will last 6 hours without crashing while running these( i would run both at the same time to get more accurate results since its a dual core) then restart your computer and raise the clock speed again. repeat these steps until your computer stops performing stably. it takes a really long time.
i have a core 2 duo e6600 2.4 ghz and a humungus sexy cooling fan/heatsink(it is about an inch away from touching my side panel so you can imagine how big it is.) i also have 4 case fans, 3 psu fans, and 1 vga fan, and these 2 little pci slot case fans sitting right next to my vga on either side(it is literally about a millimeter away from my gpu, that means awesome cooling times infinity). my vga idles at about 52 and loads at about 72 which is pretty decent. i will assume that my cpu is extremely cool because of the big cooling system but i never checked it. im choosing not to mess with it because keep in mind that the cpu is not made to perform at higher speeds and overclocking can possibly shorten its life span.