Okay, do NOT set your memory to 2.9 volts, that will FRY it in like two seconds. You have DDR2 memory, which uses lower volts than DDR RAM, and just by checking the web link you posted I saw that you have the correct voltage on the RAM.
My suggestion is don't fool with it until you read up on overclocking. There is a massive amount of information on the web about it; try reading up in general about it and then ask specific questions here, and we can help you out more. You don't always get a good overclock depending on how "lucky" you are (steppings of CPU's and such). Also, having 4 sticks of memory stresses the memory controller (I believe that holds true for socket AM2 as well as 939, but don't quote me on that).
X1337, honestly, if he had tried increasing his RAM voltage that much, he could have really fried his RAM. Be careful with such definitive answers! Thanks.