well, basically, there are different things you can OC. The three things I know of that you can OC are your CPU, Memory, and gaphics card. When OCing graohics cards, you can usually do it no matter what, repending that it can handle what you're trying to OC it to ofcourse. However, when OCing CPU and memory, you need to have a compatible motherboard. As has been said, your Dell motherboard isn't compatable for OCing CPU and mem, so if you want to OC them you'd need a new motherboard. In some cases, you can use a BIOS to unlock the motherboard so that it will let you OC them, but sometimes this doesn't work, because there isn't a BIOS available. If you want to try finding a BIOS, you'd need to ask someone else, I don't know much about that.
If you're not comfortable with doing that, then I'd say just leave it as is, because you already have a very fast CPU and
LOTS of RAM for a homeuse machine.
Now, when it comes to OCing your graphics card, you don't need a compatible motherboard, so you can just use ATITool to do it.
(btw, in your sig, you have "530mhzcore/530mhzmemory=1060mhz". Unless I'm deaply mistaken, they don't add up like that

)